Fatal error raised when clicking on the sidebar CiviCRM link

[ferdi2005]

When clicking the sidebar CiviCRM link this plugin raises a fatal error:

Un errore di E_ERROR è stato causato nella linea 61 del file /home/[REDACTED]/wp-content/plugins/official-facebook-pixel/vendor/guzzlehttp/guzzle/src/functions.php. Messaggio di errore: Uncaught Error: Call to undefined method GuzzleHttp\Utils::chooseHandler() in /home/[REDACTED]/wp-content/plugins/official-facebook-pixel/vendor/guzzlehttp/guzzle/src/functions.php:61
Stack trace:
#0 /home/[REDACTED]/wp-content/plugins/civicrm/civicrm/vendor/guzzlehttp/guzzle/src/HandlerStack.php(42): GuzzleHttp\choose_handler()
#1 /home/[REDACTED]/wp-content/plugins/civicrm/civicrm/vendor/guzzlehttp/guzzle/src/Client.php(65): GuzzleHttp\HandlerStack::create()
#2 /home/[REDACTED]/wp-content/plugins/civicrm/civicrm/CRM/Utils/Check/Component.php(135): GuzzleHttp\Client->__construct()
#3 /home/[REDACTED]/wp-content/plugins/civicrm/civicrm/CRM/Utils/Check/Component/Security.php(349): CRM_Utils_Check_Component->fileExists('https://[REDACTED]...')
#4 /home/[REDACTED]/wp-content/plugins/civicrm/civicrm/CRM/Utils/Check/Component/Security.php(119): CRM_Utils_Check_Component_Security->isDirAccessible('/home/[REDACTED]/...', 'https://[REDACTED].

This doesn't happen when opening directly the admin area reloading the page.