after changing the permitions to try solutions I reset the permitions. So the folder "admin" ist 755 and the files are 644
Just the files in the admin folder (as there is not an editor to edit the admin files), files outside of this folder can retain 666.
Is an error being logged in your server error logs? Have you modified the English language files that came with v7.6.0? Have you re-translated all of the language strings to your native language (I ask as language files from another version could cause problems as well).
