Class 'Str' not found

#1

October cms suddenly stopped and showing

(1/1) Error

Class ‘Str’ not found
in Application.php line 390
at Application->October\Rain\Foundation{closure}(‘Illuminate\Broadcasting\BroadcastServiceProvider’, 0)in EnumeratesValues.php line 371

#2

Try these commands

php artisan cache:clear
composer update
#3

everything tried, not working