How do I fix zombie processes?

A zombie is already dead, so you cannot kill it. To clean up a zombie, it must be waited on by its parent, so killing the parent should work to eliminate the zombie. (After the parent dies, the zombie will be inherited by pid 1, which will wait on it and clear its entry in the process table.)

How do I see zombie processes in Linux?

Zombie processes can be found easily with the ps command. Within the ps output there is a STAT column which will show the processes current status, a zombie process will have Z as the status.