TypeError: Symfony\Component\HttpFoundation\InputBag::get(): Argument #1 ($key) must be of type string, null given, called in /var/www/html/docroot/core/lib/Drupal/Core/Routing/RouteMatch.php on line 127 in Symfony\Component\HttpFoundation\InputBag->get()

What did you do to trigger this error message? This feels like an incomplete routing definition somewhere.

In my case, after updating the core version to 10.2.2
In /admin/config/people/accounts

TypeError: Symfony\Component\HttpFoundation\InputBag::get(): Argument #1 ($key) must be of type string, null given, called in /code/web/core/lib/Drupal/Core/Routing/RouteMatch.php on line 127 in Symfony\Component\HttpFoundation\InputBag->get() (line 29 of /code/vendor/symfony/http-foundation/InputBag.php).
Drupal\Core\Routing\RouteMatch->getRawParameter() (Line: 61)
Drupal\workflow_field_groups\Access\WorkflowFieldGroupsAccessCheck->access()
call_user_func_array() (Line: 160)
Drupal\Core\Access\AccessManager->performCheck() (Line: 136)
Drupal\Core\Access\AccessManager->check() (Line: 93)
...

In my case, it is caused by a module that is not supported anymore but is still in use: workflow_field_groups

On this line web/core/lib/Drupal/Core/Routing/RouteMatch.php on line 127 $parameter_name is NULL

  public function getParameter($parameter_name) {
    return $this->parameters->get($parameter_name);
  }

Preventing this from happening could be done by patching this line
return $this->parameters->get($parameter_name);
to this
return $this->parameters->get($parameter_name ?? '');

The fix should be made in workflow_field_groups, why is it calling getParameter(NULL)?