Tramp signals 'remote-file-error' consequently

* doc/misc/tramp.texi (External packages): Mention also special events.
Emphasise, that Tramp raises remote-file-error.

* etc/NEWS: Tramp signals 'remote-file-error' consequently.
Presentational fixes and improvements.

* lisp/net/tramp.el (tramp-skeleton-process-file)
(tramp-handle-make-symbolic-link, tramp-process-actions)
(tramp-wait-for-regexp, tramp-send-string):
* lisp/net/tramp-adb.el (tramp-adb-get-device)
(tramp-adb-send-command-and-check, tramp-adb-barf-unless-okay)
(tramp-adb-wait-for-output, tramp-adb-maybe-open-connection):
* lisp/net/tramp-archive.el (tramp-archive-handle-not-implemented):
* lisp/net/tramp-crypt.el (tramp-crypt-do-encrypt-or-decrypt-file-name)
(tramp-crypt-do-encrypt-or-decrypt-file):
* lisp/net/tramp-gvfs.el (tramp-gvfs-dbus-event-error)
(tramp-gvfs-maybe-open-connection):
* lisp/net/tramp-sh.el
(tramp-do-directory-files-and-attributes-with-perl)
(tramp-do-copy-or-rename-file-directly)
(tramp-do-copy-or-rename-file-out-of-band)
(tramp-sh-handle-file-local-copy, tramp-sh-handle-write-region)
(tramp-bundle-read-file-names, tramp-maybe-send-script)
(tramp-find-file-exists-command, tramp-barf-if-no-shell-prompt)
(tramp-maybe-open-connection, tramp-wait-for-output)
(tramp-send-command-and-check, tramp-barf-unless-okay)
(tramp-send-command-and-read, tramp-get-ls-command):
* lisp/net/tramp-smb.el (tramp-smb-handle-file-attributes)
(tramp-smb-handle-make-symbolic-link)
(tramp-smb-maybe-open-connection, tramp-smb-call-winexe):
* lisp/net/tramp-sshfs.el (tramp-sshfs-maybe-open-connection):
* lisp/net/tramp-sudoedit.el (tramp-sudoedit-send-command-and-read):
Raise a `remote-file-error' in case of connection problems.

* lisp/net/tramp-rclone.el (tramp-rclone-maybe-open-connection): Improve
check for host.

* lisp/net/tramp-smb.el (tramp-smb-get-localname): Improve error message.

* lisp/net/tramp-sudoedit.el (tramp-default-host-alist):
Set a default for "sudoedit" method.
(tramp-sudoedit-maybe-open-connection): Check for proper host name.
(tramp-sudoedit-send-command): Do not expand ?h.

* lisp/net/tramp.el (tramp-compute-multi-hops): Check for cycle
proxy definition.

* test/lisp/net/tramp-archive-tests.el (tramp-archive-test20-file-modes)
(tramp-archive-test21-file-links): Check for `rmote-file-error'.

* test/lisp/net/tramp-tests.el (tramp-file-name-with-sudo): Declare.
(tramp--test-ignore-make-symbolic-link-error): Check for
`rmote-file-error'.
(tramp-test03-file-name-method-rules): Delete.
(tramp-test03-file-error): New test.
(tramp--test-supports-processes-p): Make it more rebust.

14 files changed, 186 insertions, 134 deletions

diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index c916588a060..73c3e1ed326 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -6658,7 +6658,7 @@ root directory, it is most likely sufficient to make the
 @code{default-directory} of the process buffer as the root directory.
 
 
-@subsection Timers, process filters, process sentinels, redisplay
+@subsection Timers, process filters, process sentinels, special events, redisplay
 
 @vindex remote-file-error
 Timers run asynchronously at any time when Emacs is waiting for
@@ -6678,7 +6678,13 @@ wrapping the timer function body as follows:
 @end lisp
 
 A similar problem could happen with process filters, process
-sentinels, and redisplay (updating the mode line).
+sentinels, special event handlers, and redisplay (updating the mode
+line).
+
+@strong{Note} that @value{tramp} raises a @code{remote-file-error}
+error for any connection-related problem.  You can protect against all
+such problems with the code snippet above (or with a
+@code{condition-case} form with a @code{remote-file-error} handler).
 
 
 @node Extension packages
diff --git a/etc/NEWS b/etc/NEWS
index 076a4e2c15e..02185050e12 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -62,7 +62,7 @@ You can keep the old behavior by putting '(xterm-mouse-mode -1)' in your
 init file.
 
 +++
-** 'site-start.el' is now loaded before the user's early init file.
+** site-start.el is now loaded before the user's early init file.
 Previously, the order was early-init.el, site-start.el and then the
 user's regular init file, but now site-start.el comes first.  This
 allows site administrators to customize things that can normally only be
@@ -2183,6 +2183,12 @@ To unconditionally enable 'flyspell-mode' from a hook, use this instead:
 ** Tramp
 
 +++
+*** Tramp signals 'remote-file-error' in case of connection problems.
+This is a subcategory of 'file-error'.  Therefore, all checks for
+'file-error' in 'condition-case', 'ignore-error', 'error-conditions' and
+alike still work.
+
++++
 *** New command 'tramp-cleanup-bufferless-connections'.
 Connection-related objects for which no associated buffers exist, except
 for Tramp internal buffers, are flushed.  This is helpful to prune
@@ -3352,7 +3358,7 @@ changing the marking state in the calendar buffer.
 A new library has been added to the calendar for handling iCalendar
 (RFC5545) data.  The library is designed for reuse in other parts of
 Emacs and in third-party packages.  Package authors can find the new
-library in the Emacs distribution under lisp/calendar/icalendar-*.el.
+library in the Emacs distribution under "lisp/calendar/icalendar-*.el".
 
 Most of the functions and variables in the older icalendar.el have been
 marked obsolete and now suggest appropriate replacements from the new
@@ -3605,7 +3611,7 @@ This package provides platform-neutral interfaces to block your system
 from entering idle sleep and a hook to process pre-sleep and post-wake
 events.  You can use this to avoid the system entering an idle sleep
 state and interrupting a long-running process due to lack of user
-activity.  The sleep event hook lets you, for example close external
+activity.  The sleep event hook lets you, for example, close external
 connections or serial ports before sleeping, and reestablish them when
 the system wakes up.
 
@@ -3615,6 +3621,7 @@ blocking requires org.freedesktop.Screensaver service), macOS
 (sleep/display blocking requires version 10.9 or later, sleep events are
 supported on all versions), MS-Windows (sleep blocking is supported on
 all versions, sleep events require Windows 8 or later).
+
 
 * Incompatible Lisp Changes in Emacs 31.1
 
@@ -3788,6 +3795,7 @@ When no tags file is loaded, symbol completion just won't provide any
 suggestions.  So the 'M-?' command now works without a tags table.  And
 the 'M-.' will show a message describing the several built-in options
 that will provide an Xref backend when used.
+
 
 * Lisp Changes in Emacs 31.1
 
diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index 5bcb92536fd..c20b5df9b59 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -974,7 +974,7 @@ E.g. a host name \"192.168.1.1#5555\" returns \"192.168.1.1:5555\"
               (sleep-for 0.1)
               host)
              (t (tramp-error
-                 vec 'file-error "Could not find device %s" host)))))))
+                 vec 'remote-file-error "Could not find device %s" host)))))))
 
 (defun tramp-adb-execute-adb-command (vec &rest args)
   "Execute an adb command.
@@ -1047,7 +1047,7 @@ the exit status."
   (with-current-buffer (tramp-get-connection-buffer vec)
     (unless (tramp-search-regexp (rx "tramp_exit_status " (+ digit)))
       (tramp-error
-       vec 'file-error "Couldn't find exit status of `%s'" command))
+       vec 'remote-file-error "Couldn't find exit status of `%s'" command))
     (skip-chars-forward "^ ")
     (prog1
         (if exit-status
@@ -1060,13 +1060,14 @@ the exit status."
   "Run COMMAND, check exit status, throw error if exit status not okay.
 FMT and ARGS are passed to `error'."
   (unless (tramp-adb-send-command-and-check vec command)
-    (apply #'tramp-error vec 'file-error fmt args)))
+    (apply #'tramp-error vec 'remote-file-error fmt args)))
 
 (defun tramp-adb-wait-for-output (proc &optional timeout)
   "Wait for output from remote command."
   (unless (buffer-live-p (process-buffer proc))
     (delete-process proc)
-    (tramp-error proc 'file-error "Process `%s' not available, try again" proc))
+    (tramp-error
+     proc 'remote-file-error "Process `%s' not available, try again" proc))
   (let ((prompt (tramp-get-connection-property proc "prompt" tramp-adb-prompt)))
     (with-current-buffer (process-buffer proc)
       (if (tramp-wait-for-regexp proc timeout prompt)
@@ -1085,10 +1086,11 @@ FMT and ARGS are passed to `error'."
               (delete-region (point) (point-max))))
         (if timeout
             (tramp-error
-             proc 'file-error
+             proc 'remote-file-error
              "[[Remote prompt `%s' not found in %d secs]]" prompt timeout)
           (tramp-error
-           proc 'file-error "[[Remote prompt `%s' not found]]" prompt))))))
+           proc 'remote-file-error
+           "[[Remote prompt `%s' not found]]" prompt))))))
 
 (defun tramp-adb-maybe-open-connection (vec)
   "Maybe open a connection VEC.
@@ -1110,13 +1112,14 @@ connection if a previous connection has died for some reason."
       ;; whether it is still the same device.
       (when
           (and user (not (tramp-get-connection-property vec " su-command-p" t)))
-        (tramp-error vec 'file-error "Cannot switch to user `%s'" user))
+        (tramp-error vec 'remote-file-error "Cannot switch to user `%s'" user))
 
       (unless (process-live-p p)
         (save-match-data
           (when (and p (processp p)) (delete-process p))
           (if (tramp-string-empty-or-nil-p device)
-              (tramp-error vec 'file-error "Device %s not connected" host))
+              (tramp-error
+               vec 'remote-file-error "Device %s not connected" host))
           (with-tramp-progress-reporter vec 3 "Opening adb shell connection"
             (let* ((coding-system-for-read 'utf-8-dos) ; Is this correct?
                    (process-connection-type tramp-process-connection-type)
@@ -1137,7 +1140,7 @@ connection if a previous connection has died for some reason."
               (tramp-send-string vec tramp-rsh-end-of-line)
               (tramp-adb-wait-for-output p 30)
               (unless (process-live-p p)
-                (tramp-error vec 'file-error "Terminated!"))
+                (tramp-error vec 'remote-file-error "Terminated!"))
 
               ;; Set connection-local variables.
               (tramp-set-connection-local-variables vec)
@@ -1193,7 +1196,7 @@ connection if a previous connection has died for some reason."
                   ;; Do not flush, we need the nil value.
                   (tramp-set-connection-property vec " su-command-p" nil)
                   (tramp-error
-                   vec 'file-error "Cannot switch to user `%s'" user)))
+                   vec 'remote-file-error "Cannot switch to user `%s'" user)))
 
               ;; Mark it as connected.
               (tramp-set-connection-property p "connected" t))))))))
diff --git a/lisp/net/tramp-archive.el b/lisp/net/tramp-archive.el
index a4323156c2a..e970fd1cd56 100644
--- a/lisp/net/tramp-archive.el
+++ b/lisp/net/tramp-archive.el
@@ -737,7 +737,7 @@ offered."
               (apply #'tramp-archive-file-name-for-operation operation args)))))
     (tramp-message v 10 "%s" (cons operation args))
     (tramp-error
-     v 'file-error
+     v 'remote-file-error
      "Operation `%s' not implemented for file archives" operation)))
 
 (add-hook 'tramp-unload-hook
diff --git a/lisp/net/tramp-crypt.el b/lisp/net/tramp-crypt.el
index 565b9f0a5aa..59e4cea2edb 100644
--- a/lisp/net/tramp-crypt.el
+++ b/lisp/net/tramp-crypt.el
@@ -446,7 +446,7 @@ Otherwise, return NAME."
                      crypt-vec (if (eq op 'encrypt) "encode" "decode")
                      tramp-compat-temporary-file-directory localname)
               (tramp-error
-               crypt-vec 'file-error "%s of file name %s failed"
+               crypt-vec 'remote-file-error "%s of file name %s failed"
                (if (eq op 'encrypt) "Encoding" "Decoding") name))
             (with-current-buffer (tramp-get-connection-buffer crypt-vec)
               (goto-char (point-min))
@@ -481,7 +481,7 @@ Raise an error if this fails."
                (file-name-directory infile)
                (concat "/" (file-name-nondirectory infile)))
         (tramp-error
-         crypt-vec 'file-error "%s of file %s failed"
+         crypt-vec 'remote-file-error "%s of file %s failed"
          (if (eq op 'encrypt) "Encrypting" "Decrypting") infile))
       (with-current-buffer (tramp-get-connection-buffer crypt-vec)
         (write-region nil nil outfile)))))
diff --git a/lisp/net/tramp-gvfs.el b/lisp/net/tramp-gvfs.el
index 64efce227d6..0f68e4d768a 100644
--- a/lisp/net/tramp-gvfs.el
+++ b/lisp/net/tramp-gvfs.el
@@ -1006,7 +1006,7 @@ The global value will always be nil; it is bound where needed.")
   "Called when a D-Bus error message arrives, see `dbus-event-error-functions'."
   (when tramp-gvfs-dbus-event-vector
     (tramp-message tramp-gvfs-dbus-event-vector 6 "%S" event)
-    (tramp-error tramp-gvfs-dbus-event-vector 'file-error (cadr err))))
+    (tramp-error tramp-gvfs-dbus-event-vector 'remote-file-error (cadr err))))
 
 (add-hook 'dbus-event-error-functions #'tramp-gvfs-dbus-event-error)
 (add-hook 'tramp-gvfs-unload-hook
@@ -2234,7 +2234,7 @@ connection if a previous connection has died for some reason."
                    method)
                tramp-gvfs-mounttypes)
         (tramp-error
-         vec 'file-error "Method `%s' not supported by GVFS" method)))
+         vec 'remote-file-error "Method `%s' not supported by GVFS" method)))
 
     ;; For password handling, we need a process bound to the
     ;; connection buffer.  Therefore, we create a dummy process.
@@ -2332,10 +2332,10 @@ connection if a previous connection has died for some reason."
                 vec 'tramp-connection-timeout tramp-connection-timeout)
                (if (tramp-string-empty-or-nil-p user-domain)
                    (tramp-error
-                    vec 'file-error
+                    vec 'remote-file-error
                     "Timeout reached mounting %s using %s" host-port method)
                  (tramp-error
-                  vec 'file-error
+                  vec 'remote-file-error
                   "Timeout reached mounting %s@%s using %s"
                   user-domain host-port method)))
             (while (not (tramp-get-file-property vec "/" "fuse-mountpoint"))
@@ -2345,7 +2345,7 @@ connection if a previous connection has died for some reason."
           ;; is marked with the fuse-mountpoint "/".  We shall react.
           (when (string-equal
                  (tramp-get-file-property vec "/" "fuse-mountpoint" "") "/")
-            (tramp-error vec 'file-error "FUSE mount denied"))
+            (tramp-error vec 'remote-file-error "FUSE mount denied"))
 
           ;; Save the password.
           (ignore-errors
diff --git a/lisp/net/tramp-rclone.el b/lisp/net/tramp-rclone.el
index 6b0daeba2ac..cd5c3f46f54 100644
--- a/lisp/net/tramp-rclone.el
+++ b/lisp/net/tramp-rclone.el
@@ -381,53 +381,53 @@ connection if a previous connection has died for some reason."
 
   (with-tramp-debug-message vec "Opening connection"
     (let ((host (tramp-file-name-host vec)))
-      (when (rassoc `(,host) (tramp-rclone-parse-device-names nil))
-        (if (tramp-string-empty-or-nil-p host)
-            (tramp-error vec 'file-error "Storage %s not connected" host))
-        ;; We need a process bound to the connection buffer.
-        ;; Therefore, we create a dummy process.  Maybe there is a
-        ;; better solution?
-        (unless (get-buffer-process (tramp-get-connection-buffer vec))
-          (let ((p (make-network-process
-                    :name (tramp-get-connection-name vec)
-                    :buffer (tramp-get-connection-buffer vec)
-                    :server t :host 'local :service t :noquery t)))
-            (tramp-post-process-creation p vec)
-
-            ;; Set connection-local variables.
-            (tramp-set-connection-local-variables vec)))
-
-        ;; Create directory.
-        (unless (file-directory-p (tramp-fuse-mount-point vec))
-          (make-directory (tramp-fuse-mount-point vec) 'parents))
-
-        ;; Mount.  This command does not return, so we use 0 as
-        ;; DESTINATION of `tramp-call-process'.
-        (unless (tramp-fuse-mounted-p vec)
-          (apply
-           #'tramp-call-process
-           vec tramp-rclone-program nil 0 nil
-           "mount" (tramp-fuse-mount-spec vec)
-           (tramp-fuse-mount-point vec)
-           (tramp-get-method-parameter vec 'tramp-mount-args))
-          (while (not (file-exists-p (tramp-make-tramp-file-name vec 'noloc)))
-            (tramp-cleanup-connection vec 'keep-debug 'keep-password))
-          (add-to-list 'tramp-fuse-mount-points (tramp-file-name-unify vec)))
-
-        ;; Mark it as connected.
-        (tramp-set-connection-property
-         (tramp-get-connection-process vec) "connected" t)))
-
-    ;; In `tramp-check-cached-permissions', the connection properties
-    ;; "{uid,gid}-{integer,string}" are used.  We set them to proper values.
-    (with-tramp-connection-property
-        vec "uid-integer" (tramp-get-local-uid 'integer))
-    (with-tramp-connection-property
-        vec "gid-integer" (tramp-get-local-gid 'integer))
-    (with-tramp-connection-property
-        vec "uid-string" (tramp-get-local-uid 'string))
-    (with-tramp-connection-property
-        vec "gid-string" (tramp-get-local-gid 'string))))
+      (when (or (tramp-string-empty-or-nil-p host)
+                (not (rassoc `(,host) (tramp-rclone-parse-device-names nil))))
+        (tramp-error vec 'remote-file-error "Storage %s not connected" host))
+
+      ;; We need a process bound to the connection buffer.  Therefore,
+      ;; we create a dummy process.  Maybe there is a better solution?
+      (unless (get-buffer-process (tramp-get-connection-buffer vec))
+        (let ((p (make-network-process
+                  :name (tramp-get-connection-name vec)
+                  :buffer (tramp-get-connection-buffer vec)
+                  :server t :host 'local :service t :noquery t)))
+          (tramp-post-process-creation p vec)
+
+          ;; Set connection-local variables.
+          (tramp-set-connection-local-variables vec)))
+
+      ;; Create directory.
+      (unless (file-directory-p (tramp-fuse-mount-point vec))
+        (make-directory (tramp-fuse-mount-point vec) 'parents))
+
+      ;; Mount.  This command does not return, so we use 0 as
+      ;; DESTINATION of `tramp-call-process'.
+      (unless (tramp-fuse-mounted-p vec)
+        (apply
+         #'tramp-call-process
+         vec tramp-rclone-program nil 0 nil
+         "mount" (tramp-fuse-mount-spec vec)
+         (tramp-fuse-mount-point vec)
+         (tramp-get-method-parameter vec 'tramp-mount-args))
+        (while (not (file-exists-p (tramp-make-tramp-file-name vec 'noloc)))
+          (tramp-cleanup-connection vec 'keep-debug 'keep-password))
+        (add-to-list 'tramp-fuse-mount-points (tramp-file-name-unify vec)))
+
+      ;; Mark it as connected.
+      (tramp-set-connection-property
+       (tramp-get-connection-process vec) "connected" t)))
+
+  ;; In `tramp-check-cached-permissions', the connection properties
+  ;; "{uid,gid}-{integer,string}" are used.  We set them to proper values.
+  (with-tramp-connection-property
+      vec "uid-integer" (tramp-get-local-uid 'integer))
+  (with-tramp-connection-property
+      vec "gid-integer" (tramp-get-local-gid 'integer))
+  (with-tramp-connection-property
+      vec "uid-string" (tramp-get-local-uid 'string))
+  (with-tramp-connection-property
+      vec "gid-string" (tramp-get-local-gid 'string)))
 
 (defun tramp-rclone-send-command (vec &rest args)
   "Send a command to connection VEC.
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index 97b72ba00ad..13e886b2c13 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -1969,7 +1969,7 @@ ID-FORMAT valid values are `string' and `integer'."
          (tramp-send-command-and-read
           vec (format "tramp_perl_directory_files_and_attributes %s"
                       (tramp-shell-quote-argument localname)))))
-    (when (stringp object) (tramp-error vec 'file-error object))
+    (when (stringp object) (tramp-error vec 'remote-file-error object))
     object))
 
 ;; FIXME: Fix function to work with count parameter.
@@ -2378,7 +2378,7 @@ the uid and gid from FILENAME."
                         ((eq op 'copy) "cp -f")
                         ((eq op 'rename) "mv -f")
                         (t (tramp-error
-                            v 'file-error
+                            v 'remote-file-error
                             "Unknown operation `%s', must be `copy' or `rename'"
                             op))))
              (localname1 (tramp-file-local-name filename))
@@ -2608,7 +2608,7 @@ The method used must be an out-of-band method."
       ;; Check for local copy program.
       (unless (executable-find copy-program)
         (tramp-error
-         v 'file-error "Cannot find local copy program: %s" copy-program))
+         v 'remote-file-error "Cannot find local copy program: %s" copy-program))
 
       ;; Install listener on the remote side.  The prompt must be
       ;; consumed later on, when the process does not listen anymore.
@@ -2618,7 +2618,7 @@ The method used must be an out-of-band method."
                   (tramp-find-executable
                    v remote-copy-program (tramp-get-remote-path v)))
           (tramp-error
-           v 'file-error
+           v 'remote-file-error
            "Cannot find remote listener: %s" remote-copy-program))
         (setq remote-copy-program
               (string-join
@@ -2629,7 +2629,7 @@ The method used must be an out-of-band method."
         (tramp-send-command v remote-copy-program)
         (with-timeout
             (60 (tramp-error
-                 v 'file-error
+                 v 'remote-file-error
                  "Listener process not running on remote host: `%s'"
                  remote-copy-program))
           (tramp-send-command v (format "netstat -l | grep -q :%s" listener))
@@ -3468,7 +3468,8 @@ will be used."
 
                ;; Oops, I don't know what to do.
                (t (tramp-error
-                   v 'file-error "Wrong method specification for `%s'" method)))
+                   v 'remote-file-error
+                   "Wrong method specification for `%s'" method)))
 
             ;; Error handling.
             ((error quit)
@@ -3663,7 +3664,7 @@ will be used."
              ;; That's not expected.
              (t
               (tramp-error
-               v 'file-error
+               v 'remote-file-error
                (concat "Method `%s' should specify both encoding and "
                        "decoding command or an scp program")
                method)))))))))
@@ -3689,7 +3690,7 @@ are \"file-exists-p\", \"file-readable-p\", \"file-directory-p\" and
                      tramp-end-of-heredoc
                      (mapconcat #'tramp-shell-quote-argument files "\n")
                      tramp-end-of-heredoc))
-             (tramp-error vec 'file-error "%s" (tramp-get-buffer-string)))
+             (tramp-error vec 'remote-file-error "%s" (tramp-get-buffer-string)))
            ;; Read the expression.
            (goto-char (point-min))
            (read (current-buffer))))
@@ -4165,7 +4166,7 @@ Only send the definition if it has not already been done."
         ;; Expand format specifiers.
         (unless (setq script (tramp-expand-script vec script))
           (tramp-error
-           vec 'file-error
+           vec 'remote-file-error
            (format "Script %s is not applicable on remote host" name)))
         ;; Send it.
         (tramp-barf-unless-okay
@@ -4325,13 +4326,15 @@ file exists and nonzero exit status otherwise."
              ;; We cannot use `tramp-get-ls-command', this results in an infloop.
              ;; (Bug#65321)
              (ignore-errors
-               (and (setq result (format "ls -d >%s" (tramp-get-remote-null-device vec)))
+               (and (setq
+                     result
+                     (format "ls -d >%s" (tramp-get-remote-null-device vec)))
                     (tramp-send-command-and-check
                      vec (format "%s %s" result existing))
                     (not (tramp-send-command-and-check
                           vec (format "%s %s" result nonexistent))))))
       (tramp-error
-       vec 'file-error "Couldn't find command to check if file exists"))
+       vec 'remote-file-error "Couldn't find command to check if file exists"))
     (tramp-set-file-property vec existing "file-exists-p" t)
     result))
 
@@ -4484,7 +4487,8 @@ seconds.  If not, it produces an error message with the given ERROR-ARGS."
       (error
        (delete-process proc)
        (apply #'tramp-error-with-buffer
-              (tramp-get-connection-buffer vec) vec 'file-error error-args)))))
+              (tramp-get-connection-buffer vec) vec
+              'remote-file-error error-args)))))
 
 (defvar tramp-config-check nil
   "A function to be called with one argument, VEC.
@@ -5293,8 +5297,8 @@ connection if a previous connection has died for some reason."
             (unless (and (process-live-p p)
                          (tramp-wait-for-output p 10))
               ;; The error will be caught locally.
-              (tramp-error vec 'file-error "Awake did fail")))
-        (file-error
+              (tramp-error vec 'remote-file-error "Awake did fail")))
+        (remote-file-error
          (tramp-cleanup-connection vec t)
          (setq p nil)))
 
@@ -5314,7 +5318,8 @@ connection if a previous connection has died for some reason."
                       (setenv "HISTFILESIZE" "0")
                       (setenv "HISTSIZE" "0"))))
               (unless (stringp tramp-encoding-shell)
-                (tramp-error vec 'file-error "`tramp-encoding-shell' not set"))
+                (tramp-error
+                 vec 'remote-file-error "`tramp-encoding-shell' not set"))
               (let* ((current-host tramp-system-name)
                      (target-alist (tramp-compute-multi-hops vec))
                      (previous-hop tramp-null-hop)
@@ -5520,7 +5525,8 @@ function waits for output unless NOOUTPUT is set."
   "Wait for output from remote command."
   (unless (buffer-live-p (process-buffer proc))
     (delete-process proc)
-    (tramp-error proc 'file-error "Process `%s' not available, try again" proc))
+    (tramp-error
+     proc 'remote-file-error "Process `%s' not available, try again" proc))
   (with-current-buffer (process-buffer proc)
     (let* (;; Initially, `tramp-end-of-output' is "#$ ".  There might
            ;; be leading ANSI control escape sequences, which must be
@@ -5551,11 +5557,11 @@ function waits for output unless NOOUTPUT is set."
               (delete-region (point) (point-max))))
         (if timeout
             (tramp-error
-             proc 'file-error
+             proc 'remote-file-error
              "[[Remote prompt `%s' not found in %d secs]]"
              tramp-end-of-output timeout)
           (tramp-error
-           proc 'file-error
+           proc 'remote-file-error
            "[[Remote prompt `%s' not found]]" tramp-end-of-output)))
       ;; Return value is whether end-of-output sentinel was found.
       found)))
@@ -5594,7 +5600,7 @@ the exit status."
   (with-current-buffer (tramp-get-connection-buffer vec)
     (unless (tramp-search-regexp (rx "tramp_exit_status " (+ digit)))
       (tramp-error
-       vec 'file-error "Couldn't find exit status of `%s'" command))
+       vec 'remote-file-error "Couldn't find exit status of `%s'" command))
     (skip-chars-forward "^ ")
     (prog1
         (if exit-status
@@ -5608,7 +5614,7 @@ the exit status."
 Similar to `tramp-send-command-and-check' but accepts two more arguments
 FMT and ARGS which are passed to `error'."
   (or (tramp-send-command-and-check vec command)
-      (apply #'tramp-error vec 'file-error fmt args)))
+      (apply #'tramp-error vec 'remote-file-error fmt args)))
 
 (defun tramp-send-command-and-read (vec command &optional noerror marker)
   "Run COMMAND and return the output, which must be a Lisp expression.
@@ -5627,7 +5633,7 @@ raises an error."
             (search-forward-regexp marker)
           (error (unless noerror
                    (tramp-error
-                    vec 'file-error
+                    vec 'remote-file-error
                     "`%s' does not return the marker `%s': `%s'"
                     command marker (buffer-string))))))
       ;; Read the expression.
@@ -5641,7 +5647,7 @@ raises an error."
               (error nil)))
         (error (unless noerror
                  (tramp-error
-                  vec 'file-error
+                  vec 'remote-file-error
                   "`%s' does not return a valid Lisp expression: `%s'"
                   command (buffer-string))))))))
 
@@ -5854,7 +5860,8 @@ Nonexistent directories are removed from spec."
                  (setq result (concat result " --color=never")))
                (throw 'ls-found result))
              (setq dl (cdr dl))))))
-     (tramp-error vec 'file-error "Couldn't find a proper `ls' command"))))
+     (tramp-error
+      vec 'remote-file-error "Couldn't find a proper `ls' command"))))
 
 (defun tramp-get-ls-command-with (vec option)
   "Return OPTION, if the remote `ls' command supports the OPTION option."
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index b87eee0fcce..554aa354c00 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -821,7 +821,7 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
   (setq filename (directory-file-name (expand-file-name filename)))
   (with-parsed-tramp-file-name filename nil
     (tramp-convert-file-attributes v localname id-format
-      (ignore-errors
+      (condition-case err
         (if (tramp-smb-get-stat-capability v)
             (tramp-smb-do-file-attributes-with-stat v)
           ;; Reading just the filename entry via "dir localname" is
@@ -851,7 +851,9 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
                     (nth 1 entry)        ;8 mode
                     nil                  ;9 gid weird
                     inode                ;10 inode number
-                    device))))))))       ;11 file system number
+                    device))))           ;11 file system number
+        (remote-file-error (signal (car err) (cdr err)))
+        (error)))))
 
 (defun tramp-smb-do-file-attributes-with-stat (vec)
   "Implement `file-attributes' for Tramp files using `stat' command."
@@ -1382,7 +1384,7 @@ will be used."
   "Like `make-symbolic-link' for Tramp files."
   (let ((v (tramp-dissect-file-name (expand-file-name linkname))))
     (unless (tramp-smb-get-cifs-capabilities v)
-      (tramp-error v 'file-error "make-symbolic-link not supported")))
+      (tramp-error v 'remote-file-error "make-symbolic-link not supported")))
 
   (tramp-skeleton-make-symbolic-link target linkname ok-if-already-exists
     (unless (tramp-smb-send-command
@@ -1571,8 +1573,7 @@ will be used."
                     (tramp-search-regexp (rx "tramp_exit_status " (+ digit)))
                   (tramp-error
                    v 'file-error
-                   "Couldn't find exit status of `%s'"
-                   tramp-smb-acl-program))
+                   "Couldn't find exit status of `%s'" tramp-smb-acl-program))
                 (skip-chars-forward "^ ")
                 (when (zerop (read (current-buffer)))
                   ;; Success.
@@ -1705,7 +1706,7 @@ If VEC has no cifs capabilities, exchange \"/\" by \"\\\\\"."
       (when (string-match-p (rx blank eol) localname)
         (tramp-error
          vec 'file-error
-         "Invalid file name %s" (tramp-make-tramp-file-name vec localname)))
+         "Invalid file name `%s'" (tramp-make-tramp-file-name vec localname)))
 
       localname)))
 
@@ -1988,7 +1989,7 @@ If ARGUMENT is non-nil, use it as argument for
           (unless tramp-smb-version
             (unless (executable-find tramp-smb-program)
               (tramp-error
-               vec 'file-error
+               vec 'remote-file-error
                "Cannot find command %s in %s" tramp-smb-program exec-path))
             (setq tramp-smb-version (shell-command-to-string command))
             (tramp-message vec 6 command)
@@ -2165,11 +2166,12 @@ Removes smb prompt.  Returns nil if an error message has appeared."
   ;; Check for program.
   (unless (executable-find tramp-smb-winexe-program)
     (tramp-error
-     vec 'file-error "Cannot find program: %s" tramp-smb-winexe-program))
+     vec 'remote-file-error "Cannot find program: %s" tramp-smb-winexe-program))
 
   ;; winexe does not supports ports.
   (when (tramp-file-name-port vec)
-    (tramp-error vec 'file-error "Port not supported for remote processes"))
+    (tramp-error
+     vec 'remote-file-error "Port not supported for remote processes"))
 
   ;; Check share.
   (unless (tramp-smb-get-share vec)
diff --git a/lisp/net/tramp-sshfs.el b/lisp/net/tramp-sshfs.el
index 338d128cc4e..2cb5b5b1ed1 100644
--- a/lisp/net/tramp-sshfs.el
+++ b/lisp/net/tramp-sshfs.el
@@ -359,7 +359,7 @@ connection if a previous connection has died for some reason."
                  vec 'tramp-mount-args nil
                  ?p (or (tramp-file-name-port vec) ""))))))
       (tramp-error
-       vec 'file-error "Error mounting %s" (tramp-fuse-mount-spec vec)))
+       vec 'remote-file-error "Error mounting %s" (tramp-fuse-mount-spec vec)))
 
     ;; Mark it as connected.
     (add-to-list 'tramp-fuse-mount-points (tramp-file-name-unify vec))
diff --git a/lisp/net/tramp-sudoedit.el b/lisp/net/tramp-sudoedit.el
index d3bb8b8478e..9511c899b2b 100644
--- a/lisp/net/tramp-sudoedit.el
+++ b/lisp/net/tramp-sudoedit.el
@@ -52,6 +52,10 @@
               `(,(rx bos (literal tramp-sudoedit-method) eos)
                 nil ,tramp-root-id-string))
 
+ (add-to-list 'tramp-default-host-alist
+              `(,(rx bos (literal tramp-sudoedit-method) eos)
+                nil ,(system-name)))
+
  (tramp-set-completion-function
   tramp-sudoedit-method tramp-completion-function-alist-su))
 
@@ -742,6 +746,10 @@ connection if a previous connection has died for some reason."
   (unless (tramp-connectable-p vec)
     (throw 'non-essential 'non-essential))
 
+  (unless (string-match-p tramp-local-host-regexp (tramp-file-name-host vec))
+    (tramp-error
+     vec 'remote-file-error "%s is not a local host" (tramp-file-name-host vec)))
+
   (with-tramp-debug-message vec "Opening connection"
     ;; We need a process bound to the connection buffer.  Therefore,
     ;; we create a dummy process.  Maybe there is a better solution?
@@ -775,7 +783,6 @@ in case of error, t otherwise."
                (append
                 (tramp-expand-args
                  vec 'tramp-sudo-login nil
-                 ?h (or (tramp-file-name-host vec) "")
                  ?u (or (tramp-file-name-user vec) ""))
                 (flatten-tree args))))
            ;; We suppress the messages `Waiting for prompts from remote shell'.
@@ -817,7 +824,7 @@ In case there is no valid Lisp expression, it raises an error."
             (when (search-forward-regexp (rx (not blank)) (line-end-position) t)
               (error nil)))
         (error (tramp-error
-                vec 'file-error
+                vec 'remote-file-error
                 "`%s' does not return a valid Lisp expression: `%s'"
                 (car args) (buffer-string)))))))
 
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index f57b572532a..5281d8e4db5 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -3931,7 +3931,7 @@ BODY is the backend specific code."
      ;; The implementation is not complete yet.
      (when (and (numberp ,destination) (zerop ,destination))
        (tramp-error
-        v 'file-error "Implementation does not handle immediate return"))
+        v 'remote-file-error "Implementation does not handle immediate return"))
 
      (let (command input tmpinput stderr tmpstderr outbuf ret)
        ;; Determine input.
@@ -5239,6 +5239,9 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
                     ?u (or (tramp-file-name-user (car target-alist)) "")
                     ?h (or (tramp-file-name-host (car target-alist)) ""))))
             (with-parsed-tramp-file-name proxy l
+              (when (member l target-alist)
+                (tramp-user-error
+                 vec "Cycle proxy definition `%s' in multi-hop" proxy))
               ;; Add the hop.
               (push l target-alist)
               ;; Start next search.
@@ -5505,7 +5508,7 @@ processes."
 This is the fallback implementation for backends which do not
 support symbolic links."
   (tramp-error
-   (tramp-dissect-file-name (expand-file-name linkname)) 'file-error
+   (tramp-dissect-file-name (expand-file-name linkname)) 'remote-file-error
    "make-symbolic-link not supported"))
 
 (defun tramp-handle-memory-info ()
@@ -6255,7 +6258,7 @@ performed successfully.  Any other value means an error."
           (tramp-clear-passwd vec)
           (delete-process proc)
           (tramp-error-with-buffer
-           (tramp-get-connection-buffer vec) vec 'file-error
+           (tramp-get-connection-buffer vec) vec 'remote-file-error
            (cond
             ((eq exit 'permission-denied) "Permission denied")
             ((eq exit 'out-of-band-failed)
@@ -6402,7 +6405,7 @@ nil."
         (tramp-accept-process-output proc)
         (unless (process-live-p proc)
           (tramp-error-with-buffer
-           nil proc 'file-error "Process has died"))
+           nil proc 'remote-file-error "Process has died"))
         (setq found (tramp-check-for-regexp proc regexp))))
     ;; The process could have timed out, for example due to session
     ;; timeout of sudo.  The process buffer does not exist any longer then.
@@ -6412,9 +6415,10 @@ nil."
     (unless found
       (if timeout
           (tramp-error
-           proc 'file-error "[[Regexp `%s' not found in %d secs]]"
+           proc 'remote-file-error "[[Regexp `%s' not found in %d secs]]"
            regexp timeout)
-        (tramp-error proc 'file-error "[[Regexp `%s' not found]]" regexp)))
+        (tramp-error
+         proc 'remote-file-error "[[Regexp `%s' not found]]" regexp)))
     found))
 
 ;; It seems that Tru64 Unix does not like it if long strings are sent
@@ -6431,7 +6435,8 @@ the remote host use line-endings as defined in the variable
          (chunksize (tramp-get-connection-property p "chunksize")))
     (unless p
       (tramp-error
-       vec 'file-error "Can't send string to remote host -- not logged in"))
+       vec 'remote-file-error
+       "Can't send string to remote host -- not logged in"))
     (tramp-set-connection-property p "last-cmd-time" (current-time))
     (tramp-message vec 10 "%s" string)
     (with-current-buffer (tramp-get-connection-buffer vec)
diff --git a/test/lisp/net/tramp-archive-tests.el b/test/lisp/net/tramp-archive-tests.el
index f3bfaac005c..79fbe38b299 100644
--- a/test/lisp/net/tramp-archive-tests.el
+++ b/test/lisp/net/tramp-archive-tests.el
@@ -757,7 +757,7 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
           ;; `set-file-modes' is not implemented.
           (should-error
            (set-file-modes tmp-name1 #o777)
-           :type 'file-error)
+           :type 'remote-file-error)
           (should (= (file-modes tmp-name1) #o400))
           (should-not (file-executable-p tmp-name1))
           (should-not (file-writable-p tmp-name1))
@@ -766,7 +766,7 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
           ;; `set-file-modes' is not implemented.
           (should-error
            (set-file-modes tmp-name2 #o777)
-           :type 'file-error)
+           :type 'remote-file-error)
           (should (= (file-modes tmp-name2) #o500))
           (should (file-executable-p tmp-name2))
           (should-not (file-writable-p tmp-name2)))
@@ -796,7 +796,7 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
           ;; `make-symbolic-link' is not implemented.
           (should-error
            (make-symbolic-link tmp-name1 tmp-name2)
-           :type 'file-error)
+           :type 'remote-file-error)
           (should (file-symlink-p tmp-name2))
           (should (file-regular-p tmp-name2))
           (should
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index bbfe15d2f59..28d773ca616 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -71,6 +71,7 @@
 (declare-function edebug-mode "edebug")
 (declare-function project-mode-line-format "project")
 (declare-function tramp-check-remote-uname "tramp-sh")
+(declare-function tramp-file-name-with-sudo "tramp-cmds")
 (declare-function tramp-find-executable "tramp-sh")
 (declare-function tramp-get-remote-chmod-h "tramp-sh")
 (declare-function tramp-get-remote-path "tramp-sh")
@@ -185,7 +186,7 @@ The temporary file is not created."
   (declare (indent defun) (debug (body)))
   `(condition-case err
        (progn ,@body)
-     (file-error
+     (remote-file-error
       (unless (string-match-p
                (rx bol (| "make-symbolic-link not supported"
                           (: "Making symbolic link"
@@ -2203,19 +2204,31 @@ being the result.")
            m))
          :type 'user-error)))))
 
-(ert-deftest tramp-test03-file-name-method-rules ()
-  "Check file name rules for some methods."
-  (skip-unless (eq tramp-syntax 'default))
-  (skip-unless (tramp--test-enabled))
-
-  ;; Multi hops are allowed for inline methods only.
-  (let (non-essential)
-    (should-error
-     (expand-file-name "/ssh:user1@host1|method:user2@host2:/path/to/file")
-     :type 'user-error)
-    (should-error
-     (expand-file-name "/method:user1@host1|ssh:user2@host2:/path/to/file")
-     :type 'user-error)))
+(ert-deftest tramp-test03-file-error ()
+  "Check that Tramp signals an error in case of connection problems."
+  ;; Connect to a non-existing host.
+  (let ((vec (copy-tramp-file-name tramp-test-vec))
+        ;; Don't poison it.
+        (tramp-default-proxies-alist tramp-default-proxies-alist)
+        (tramp-show-ad-hoc-proxies t))
+    (cl-letf* (((symbol-function #'read-string) #'ignore) ; Suppress password.
+               ((tramp-file-name-host vec) "example.com.invalid"))
+      (should-error
+       (file-exists-p (tramp-make-tramp-file-name vec))
+       ;; `user-error' is raised if the host shall be local.
+       ;; `remote-file-error' is raised if the host cannot be connected.
+       :type (if (tramp--test-ange-ftp-p)
+                 'ftp-error '(user-error remote-file-error)))
+      (should-error
+       (file-exists-p (tramp-make-tramp-file-name vec))
+       ;; `ftp-error' and `remote-file-error' are subcategories of
+       ;; `file-error'.  Let's check this as well.
+       :type '(user-error file-error))
+      ;; Check multi-hop.
+      (should-error
+       (file-exists-p
+        (tramp-file-name-with-sudo (tramp-make-tramp-file-name vec)))
+       :type '(user-error file-error)))))
 
 (ert-deftest tramp-test04-substitute-in-file-name ()
   "Check `substitute-in-file-name'."
@@ -7637,11 +7650,12 @@ This requires restrictions of file name syntax."
   (unless (tramp--test-crypt-p)
     (or (tramp--test-adb-p) (tramp--test-sh-p) (tramp--test-sshfs-p)
         (and (tramp--test-smb-p)
-             (file-writable-p
-              (file-name-concat
-               (file-remote-p ert-remote-temporary-file-directory)
-               ;; We check a directory on the "ADMIN$" share.
-               "ADMIN$" "Boot"))))))
+             (ignore-errors
+               (file-writable-p
+                (file-name-concat
+                 (file-remote-p ert-remote-temporary-file-directory)
+                 ;; We check a directory on the "ADMIN$" share.
+                 "ADMIN$" "Boot")))))))
 
 (defun tramp--test-supports-set-file-modes-p ()
   "Return whether the method under test supports setting file modes."