PHP Fatal error: Cannot redeclare check_page()

Hello,

I recently upgraded a zen cart website from 1.3.8 to 1.5.6c. Everything was working but now I started getting 500 error when I try to login to the admin. When checked logs I get

[30-Jul-2019 18:08:33 UTC] PHP Fatal error: Cannot redeclare check_page() (previously declared in /home/*****/public_html/usa/*****/includes/functions/admin_access.php:16) in /home/****/public_html/usa/*****/includes/functions/admin_profiles.php on line 76

[30-Jul-2019 18:08:33 UTC] Request URI: /usa/s3cur3/, IP address: 182.180.14.3
--> PHP Fatal error: Cannot redeclare check_page() (previously declared in /home/*****/public_html/usa/*****/includes/functions/admin_access.php:16) in /home/*****/public_html/usa/*****/includes/functions/admin_profiles.php on line 76.

Can anyone help?

Did you previously have the Admin Pages plugin installed? That was, to my remembrance, the basis for the admin-page structure used by Zen Cart since 1.5.0.

/admin/includes/functions/admin_profiles.php isn't part of original Zen Cart files.