For security reasons, you cannot connect to the back office until you have:

[Haris]

Getting after installing the prestashop. 

For security reasons, you cannot connect to the back office until you have:

renamed the /admin folder (e.g.admin502)

Rename or delete admin folder (symlink). enable debug site will work.
disable debug, site will fail, error log, var/log/prod- will show error related to admin theme accessing from "admin" folder and fail becuase it is not there.

This is fresh  install of prestashop 9.0.1-1.0. How  to fix this?

Edited 12 hours ago by Haris (see edit history)

[JBW]

Delete /var/cache. Usually admin folder is automatically renamed in installation, check your folder/file permissions