For me it turned out there were other PHP errors that were manifesting in this way. Check your console.
Topic: zend server 6 ce?
Re: zend server 6 ce?
Topic: Zend Server 6 Free Edition - License expiry?
Re: Zend Server 6 Free Edition - License expiry?
I have been notified by Zend Customer Service that Zend Server Free Edition is no longer available and that once the Expiration date is reached, the gui will no longer function.
It is unfortunate that Zend has not announced this event.
When I try your instructions for getting a free license I get an error that "Sorry, Zend Server Free Edition is no longer available."
How can I renew my free license as you have stated I should be able to do?
This appears to be caused by incorrect shutdown of the IDE.
I was able to resolve by going to my Zend/workspaces/DefaultWorkspace directory and removing (or renaming) the .metadata folder. Zend Studio should then start normally, creating a new .metadata folder.