Error 500 after manually update PS 1.7.5.1 to PS 1.7.6.5

[Marcpie]

Colleagues, I did a manual update from PS 1.7.5.1 to PS 1.7.6.5

I neatly followed the steps that are nicely explained in https://belvg.com/blog/how-to-upgrade-prestashop-step-by-step-instruction.html 

Result when logging in BO ... error 500

Debug activated via FTP, result see attachments.

What have I already done .... deleted cache via ftp (/ var / cache /) + removed cache browser and removed the 'vendor' folder from PS 1.7.5.1 and replaced (again) with 'vendor' from PS 1.7.6.5 because copying these would apparently also cause problems.

Can someone help me further? the debug results?

Thanks in advance.

[Marcpie]

Can anyone help me please ??

[JBW]

Please check if the mentioned file exist in your theme and if the access right to it are correct

[Marcpie]

Thanks JBW but...

In the meantime I was able to get back into the BO (after replacing back up but this takes ages) but now a new problem (see fig). Any modification to a module results in an error 500. HELP !!
FYI: I previously attempted a failed / interrupted update from PS 1.7.5.1 to PS 1.7.6.5
I would now like to get back into my BO and then transfer all data via migration to a clean version of PS 1.7.6.5.