Solve Lock screen button doesn’t work in Cent OS
Sometimes unexpected and strange problems arise when you start using new operating system and know very little about it. Here I will tell about tricky problem I met when using CentOS.
When you click icon Start in the bottom left corner you can observe Lock screen button - first one with lock icon
The problem was that the button stop working — just no action at all.
This was caused by creating a symbolic link python3 to specific version of Python. Apperantly desktop shell of CentOS using Python for some reason.
To solve the problem simply change the symbolic link python3 to previous version of Python
sudo ln -sf /usr/bin/python3.4 /usr/bin/python3
and reboot system.