Manual upgrade from 1.6 to 1.7 and back office error 500 problem

[zsedc]

I spent couple of days trying to upgrade PS to 1.7 . Bad luck  . Automated upgrade gives me error: 
 

[Ajax / Server Error for action upgradeDb] textStatus: "error " errorThrown:"Internal Server Error " jqXHR: "
500 Server Error

I decided to try manual upgrade https://devdocs.prestashop.com/1.7/basics/keeping-up-to-date/upgrade/ . I was so happy to se front office working with the default theme but the back office was dead. I receive ERROR 500 just after pressing LOG IN at the BO authentication screen. 

Can you help?