[TYPO3-english] after upgrade 4.7 to 6.x sys_language not visible in backend

[Domi]

Hello,

I upgraded my 4.7 to 6.0.2 and now I only get exceptional errors with 
languages. First of all in list view in root line I can't see my 
sys_language and if I try to add a new language ist simply not possible 
anymore.

Even all my translated records does not show anymore the language flag.

If I open one content element I get following database error:

Database Error
Unknown column 'sys_language.t3ver_id' in 'field list'
A SQL error occurred. This may indicate a schema mismatch between TCA 
and the database. Try running database compare in the Install Tool.

I upgraded the package and followed all steps in my install tool. The 
database compare works but does'nt show any good side effekt.

Hope someone knows anything about the changes?

Regards,
Dominic