[TYPO3] can't add content

[Franz Holzinger]

> I upgraded from typo3 3.8.1 to 4.0.
> Now I can't add any content to my page.
> 
> If I want to add a page, I get error "2: SQL error: 'Column 'media'
> cannot be null' (pages:NEW4456904932364)"
> 
> If I want to add a simple text pagecontent to one of the page, I get
> error "2: SQL error: 'Column 'l18n_diffsource' cannot be null'
> (tt_content:NEW4456914b57817)"
> 
Use the install tool and check all your database tables.

- Franz