Call to undefined function str_singular() laravel filemanager
These laravel helpers no longer exist.
Introduced on L5.8 and omitted in L6.0, these helpers are replaced by
Illuminate\Support\Str and Illuminate\Support\Arr
classes respectively.
In your example, this is replaced by Illuminate\Support\Str::singular(); etc.
Simple solution is run following command on your project terminal
You can pull them in with
composer require laravel/helpers