If eg. ~/.Xauthority is unreadable, X will spew "No protocol specified" error, but the error is singularly uninformative, and the cause cannot be found in log files either. I had to resort to strace to find out what it wanted.
Assigning to Xlib component, since those messages (which are admittedly
confusing and need help) come from XOpenDisplay() in libX11.
*** Bug 36429 has been marked as a duplicate of this bug. ***
-- GitLab Migration Automatic Message --
This bug has been migrated to freedesktop.org's GitLab instance and has been closed from further activity.
You can subscribe and participate further through the new bug through this link to our GitLab instance: https://gitlab.freedesktop.org/xorg/lib/libx11/issues/8.