PrestashopBackofficedoesnotloadmostofitemsafterupgrade1.7.5.21.7.6

Describe the bug
After upgrading from 1.7.5.2 to 1.7.6 using 1-click-upgrade most of Backoffice items do not load, this is majority of items in Backoffice sidebar menu. After clicking eg. Catalog - Products, Products page is loaded, but content shown is empty, just blank page without anything.

My shop is in maintenance mode, and when opening the shop Frontend, I can see all how it was also in 1.7.5.2. Also MySQL database has all items in tables.

Some Backoffice pages work (very few), like Catalog - Attributes.

When looking browser developer tools, I can see requested URL format is different for those Backoffice areas that work, and those that do not.

Like Catalog - Attributs that loads properly, and its URL looks like this:
..../index.php?cOntroller=AdminAttributesGroups&token=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

but like Catalog - Products, that fails to show anything, the URL looks like this:
..../index.php/sell/catalog/products?_token=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

And same patters seem to be for all working and non-working pages atfer upgrade to 1.7.6, working pages has url format "...index.php?cOntroller=...." and "...&token=".

To Reproduce
Steps to reproduce the behavior:
1. Go to 'Prestashop Backoffice'
2. Click on 'Catalog - Products'
4. Products are not listed on page

Screenshots
Find screenshots from
Catalog - Products