Unable to start DotProject after migration

[StankoStan]

Hello,
hopefully someone will be able to help here. After migration from (deprecated) cPanel, we are facing some issues:

Fatal error: Declaration of & CSS_Color::raiseError($message, $method, $line) must be compatible with & PEAR::raiseError($message = null, $code = null, $mode = null, $options = null, $userinfo = null, $error_class = null, $skipmsg = false) in /home/projekti/public_html/classes/csscolor.class.php on line 429

I've seen this error before (here as well), but mostly starting as Warning, later on with some specific error.
In this case it simple trows Fatal Error immediately. The old Server was with PHP 5.2, the newest with 8.1(2).
Any help would be appreciated, as the company wants to keep DotProject up and running.
Thanks!
Stan

[Banditpong]

Are you using an older version of dotProject like version v2.1.8? The PEAR::raiseError() function changed over the years and I believe v2.1.9 and v2.2.0 fixed this issue in csscolor.class.php, but I'm unsure on what other issues you will encounter with PHP 8.1