Today I upgraded my magento installation from 188.8.131.52 to 184.108.40.206 by doing a fresh install and selecting a database with a copy of the old database. Everything worked out well, all records of orders, invoices, products, etc have been migrated to 1.4.
I only have one problem: when I try to edit a product via Catalog > Manage products and then clicking on a product I get a Internal Server Error (500). The same thing happens when I try to create a new product after specifying the Attribute Set and Product Type and clicking on continue.
Viewing, editing or adding new categories, orders, etc is not a problem.
The strange thing is that Apache does not create an entry in the error log for these events. So I am completely in the dark.
Does anyone recognize these problems after upgrading to 1.4? Please help me.