Slim Application Error

The application could not run because of the following error:

Details

Type: ErrorException
Code: 2
Message: Undefined array key "HTTP_ACCEPT_LANGUAGE"
File: /var/www/vhosts/spokland.com/httpdocs/index.php
Line: 237

Trace

#0 /var/www/vhosts/spokland.com/httpdocs/index.php(237): Slim\Slim::handleErrors()
#1 [internal function]: {closure}()
#2 /var/www/vhosts/spokland.com/httpdocs/app/vendors/Slim/Slim.php(1191): call_user_func()
#3 /var/www/vhosts/spokland.com/httpdocs/app/vendors/Slim/Slim.php(1330): Slim\Slim->applyHook()
#4 /var/www/vhosts/spokland.com/httpdocs/app/vendors/Slim/Middleware/Flash.php(85): Slim\Slim->call()
#5 /var/www/vhosts/spokland.com/httpdocs/app/vendors/Slim/Middleware/MethodOverride.php(92): Slim\Middleware\Flash->call()
#6 /var/www/vhosts/spokland.com/httpdocs/app/vendors/Slim/Middleware/PrettyExceptions.php(67): Slim\Middleware\MethodOverride->call()
#7 /var/www/vhosts/spokland.com/httpdocs/app/vendors/Slim/Slim.php(1283): Slim\Middleware\PrettyExceptions->call()
#8 /var/www/vhosts/spokland.com/httpdocs/index.php(1837): Slim\Slim->run()
#9 {main}