Call to undefined function CodeIgniter\Router\dot_array_search()

dot_array_search() is defined in system/Helpers/array_helper.php.
Check if the file is uploaded.

Thank you, your message gave me the idea - yes, the file was there, but I noticed that folder was lowercase (system/Helper and system/Config was lowercase - Github messed up the cases). It works now when I made it uppercase, thank you again!