I’ve spent more then hour to solve this problem, so I post the solution.
Problem: after installing Zend Server on Mac OS (Snow Leopard) mysql give the error on startup:
ERROR! Manager of pid-file quit without updating file.
Most possible cause is prior mysql installations on Mac.
Type in console:
to uninstall ZS and install it again.
Explanation: obviously, official way of uninstalling ZS is incorrect, that’s way we’r using special script, witch is unmentioned in official manual.