crash after updating database (Internal Server Error)

After uploading the new files calling update.php i got following message:

Ein AJAX-HTTP-Fehler ist aufgetreten.
HTTP-Rückgabe-Code: 500
Im Folgenden finden Sie Debugging-Informationen.
Pfad: /update.php/start?id=197&op=do_nojs&op=do
Statustext: Internal Server Error
Antworttext:

The link to the error message doesnt work: i got only a blank page

Follogwing amin-pages didnt work:

http://www.aktive-arbeitslose.at/admin/config
http://www.aktive-arbeitslose.at/admin/reports/status
http://www.aktive-arbeitslose.at/admin/modules/uninstall

Uploading old version didnt work fully, because admin pages still dont work and if i call update.php there is still the outstanding update which caused the problem

image module

Saves the image style dependencies into form and view display entities.

On D8.0.1-2 i still faced some problem with modul in dev status, resulting in

"Entity/field definitions Mismatched entity and/or field definitions "

Content: Delete the URL-Alias field.
Taxonomy term: Delete the URL-Alias field.

(means that, that i have to delete these fields? how?)

What can i do to save my work, unfortunately it was a pordution site.

On my blank test site the update seemed to work well. No such problems ...

Maybe some moduls made the underlying problem. Updating drupal should not increase these problems ...