SimpleSAML\Error\UnserializableException : The option 'debug' is not an array or null

Problem/Motivation

I have just tested the following,

Drupal: 10.1.4
PHP: 8.1
drupal/simplesamlphp_auth: dev-4.x
simplesamlphp/simplesamlphp: 2.1.0-rc1

SimpleSAML\Error\UnserializableException: /var/www/html/var/config/config.php: The option 'debug' is not an array or null. in SimpleSAML\Auth\Source->initLogin() (line 197 of /var/www/html/vendor/simplesamlphp/simplesamlphp/src/SimpleSAML/Auth/Source.php).

Steps to reproduce

/simplesaml redirecting me to /simplesaml/module.php/core/welcome (Welcome page)
/saml_login is throwing "The website encountered an unexpected error. Please try again later" and getting the above error.

I have updated my config.php as per the latest version (vendor/simplesamlphp/simplesamlphp/config/config.php.dist) and tried removing the debug as well. But no luck.

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes