preg_match() Passing null to parameter #2 ($subject) of type string is deprecated.

Above is a simple solution to fix the errors in the logs.

Deprecated function: preg_match(): Passing null to parameter #2 ($subject) of type string is deprecated in Drupal\csp\Csp::Drupal\csp\{closure}() (line 507 of modules/contrib/csp/src/Csp.php).

Do you have a custom module altering the policy values, or is this reproducible by just configuring the CSP module?

Null values are not expected to be passed to setDirective or appendDirective, and are likely to cause type errors or assertion failures on CSP 2.x, so should be addressed in any code calling those methods to avoid issues when upgrading.

Thank for the reply, ill check thanks for the explanation!