Redmine

Suddenly without any reason after trying to open overview page of most of our projects one gets following error:

Internal error

An error occurred on the page you were trying to access.
If you continue to experience problems please contact your Redmine administrator for assistance.

If you are the Redmine administrator, check your log files for details about the error.

Back

There was no reconfiguration of redmine or operating system. Other pages can be opened normally.
Restarting redmine, database or even whole system does not help.
Closing apache and running redmine with WEBrick does not help either.

I have opened an issue #11374, where it is susspected that the problem is caused by one of the plugins, but did not get the answer how to track it and see what is the problem really.

Any ideas?