I have applied patch SUPEE-6788 but this breaks my store and generates an error:
Call to a member function
isTypeAllowed() on a non-object in
I have whitelisted all blocks and variables, but this problem still occurs.
I found out that replacing
Mage/Core/Model/Email/Template/Filter.php with code from before the patch solves the problem.
I can't find out how to track down the problem and solve this. Any suggestions?