Error after Contact Form testing with Swiftmailer

I have that error, after I wanted to test a Form with Swiftmailer, I had the error with send() 0, then I saw that Thread and made it exactly that way and now that error appears. I hope anyone can help me.
I’ve tried to get everything out which have anything to do with the Swiftmailer, but that didn’t help.
I don’t understand where it comes from.
Thanks for any help.

Notice: Undefined index: utility in C:\xampp\htdocs\Neos\Packages\Framework\Neos.Flow\Classes\Core\Booting\Scripts.php on line 202
Fatal error: Uncaught TypeError: Argument 1 passed to Neos\Utility\Lock\LockManager::__construct() must be of the type string, null given, called in C:\xampp\htdocs\Neos\Packages\Framework\Neos.Flow\Classes\Core\Booting\Scripts.php on line 204 and defined in C:\xampp\htdocs\Neos\Packages\Libraries\neos\utility-lock\Classes\LockManager.php:35 Stack trace: #0 C:\xampp\htdocs\Neos\Packages\Framework\Neos.Flow\Classes\Core\Booting\Scripts.php(204): Neos\Utility\Lock\LockManager->__construct(NULL, Array) #1 [internal function]: Neos\Flow\Core\Booting\Scripts::initializeConfiguration(Object(Neos\Flow\Core\Bootstrap)) #2 C:\xampp\htdocs\Neos\Packages\Framework\Neos.Flow\Classes\Core\Booting\Step.php(52): call_user_func(Array, Object(Neos\Flow\Core\Bootstrap)) #3 C:\xampp\htdocs\Neos\Packages\Framework\Neos.Flow\Classes\Core\Booting\Sequence.php(107): Neos\Flow\Core\Booting\Step->__invoke(Object(Neos\Flow\Core\Bootstrap)) #4 C:\xampp\htdocs\Neos\Packages\Framework\Neos.Flow\Classes\Core\Booting\Sequence.php(111): Neos\Flow\Core\B in C:\xampp\htdocs\Neos\Packages\Libraries\neos\utility-lock\Classes\LockManager.php on line 35

It sounds like your package versions are messed up. Flow seems to have a version that doesn’t match the lock package.

Try to fix that. The specific error shows that the Setting Neos.Flow.utility.lockStrategyClassName is empty ni your installation, but actually it should be configured in Flows Settings.