TRAMP on Emacs 26 doesn't work (macOS)

Question

I've just installed Emacs 26.3 on my macOS 10.10 (Yosemite) using the binary at Emacs for OSX Everything so far works fine icluding new package installations and different themes. However, when I tried to edit a file on my Linux server using this TRAMP line:

/myuname@myserver.com:

It returned:

File not found and directory write-protected

and a blank buffer appeared in the window area.

When I tried Emacs-25.3 binary from the same website, that same TRAMP line worked perfectly and I managed to edit file on the server. When I tried Emacs 26.1 and 26.2, the same problem occured again. So I think this problem is specific to Emacs 26.x.

What should I do to make TRAMP work on Emacs 26.x on macOS?

Answer 1

The following is an excerpt from the Quick Start Guide for Tramp, which is built-in to Emacs 26:

https://www.gnu.org/software/emacs/manual/html_node/tramp/Quick-Start-Guide.html

Tramp extends the Emacs file name syntax by a remote component. A remote file
name looks always like /method:user@host:/path/to/file.

You can use remote files exactly like ordinary files, that means you could open
a file or directory by C-x C-f /method:user@host:/path/to/file <RET>, edit the
file, and save it. You can also mix local files and remote files in file
operations with two arguments, like copy-file or rename-file. And finally, you
can run even processes on a remote host, when the buffer you call the process
from has a remote default-directory.

The O.P. has indicated in a comment that using /method:user@host:/path/to/file has resolved the issue.

• Example using ssh and a non-standard port (2222) to connect to the root default directory:

  /ssh:user@host#2222:

• Example using ssh to open a file with a non-standard port (2222):

  /ssh:user@host#2222:/path/to/file

Here is an example to connect to the root default directory using eshell with a non-standard port (2222):

(let ((default-directory "/ssh:user@host#2222:"))
  (eshell))

Here is an example to connect to the root default directory using shell with a non-standard port (2222):

(let ((default-directory "/ssh:user@host#2222:"))
  (shell))

To login automatically using an .authinfo file, here is a sample entry in that file:

machine HOST login USER password PWD

To assist with logging in automatically with a non-standard port (2222), one can use an appropriate entry in the ~/.ssh/config file, which can include other attributes; e.g., HostName and User. https://emacs.stackexchange.com/a/31339/2287

Host 12.34.567.89
  Port    2222

Answer 2

As other answers have mentioned already, Tramp has strengthened its syntax. It requires a mandatory method name now.

You could use - as method name if you mean the default method, like in /-:myuname@myserver.com:. If you don't what to apply any other method name but the default one, apply (tramp-change-syntax 'simplified). This changes Tramp syntax to /myuname@myserver.com:.

All of this is described in the Tramp manual, so you might want to read there. (Disclaimer: I'm the author of that manual).