I recently upgraded my site from 3.7 to 3.7 SP4 because I need support for .Net FrameWork 4.0. After the upgrade I created a new site and copied all my old files and and follow the instructions for the migration. Now the sites throw 'object reference not set to an instance of an object' exceptions for each and every control. This also happens when I add new controls. Everything works fine when I browse the site and even in admin interface. It's only when i enter editmode (cmspagemode=edit) this happens.
I understand that it's difficult for you to guess whats wrong but maybe you can give me some hints for configurationsettings that need to be checked etc. By the way ,the logfile doesn't show anything...
Thankful for help,
It seems that this only happens on GenericContent based controls...
EDIT - 2*******
...but not on UserControls implementing IGenericContent