X connection broken

Issue

An X application receives an error related to X connection broken. An error similar to the following appears:

X connection to localhost:10.0 broken (explicit kill or server shutdown)

There are many ways an X client can communicate to an X server:
- SSH
- UNIX socket (/tmp/.X11-unix/X11)
- TCP

This message comes from the client when suddenly it is unable to talk to the X server. This might happen for a number of reasons: network issues, the X server crashed, the client has been killed or crashed, or the communication between client and server in general is not working any more.

For example, by launching the following we can observe the error:

/usr/bin/Xvfb :11 -nolisten tcp -shmem
DISPLAY=:11.0 xclock
kill -9 <pid of Xvfb>

Shortly after on the terminal where we launched xclock we will get:

X connection to :11.0 broken (explicit kill or server shutdown).