Visvanath Ratnaweera

Yeah, masters. Just to understand the headlines one needs to switch to the geek mode. Now, running:

 

That is what Upgrading Moodle claims.

Now specific to each version there are requirements, e.g. https://moodledev.io/general/releases/4.4. According to that you have start with an 4.1.2 earliest. Here's a summary of those with system software requirements: http://www.syndrega.ch/blog/#php-and-dbms-compatibility-of-major-moodle-releases.

Moodle version 4.1 LTS and PHP 8.3? The official documentation says only PHP 7.4.0, 8.0.x and 8.1.x are supported. https://moodledev.io/general/releases/4.1

As a guest I see a Moodle site with a sophisticated theme. So the problem must be with the 'admin' account. Can you try with a non-admin account? Also without going to yoursite/admin/ page directly, try just yoursite (edit the URL in the browser address window).

 

Another simple test is to change the theme to the default "Boost". For that add the following line to your moodle/config.php:

 

If those things don't help, provide the information requested in Before you post.. read this... There were some reports of the site/admin/ page being unavailable.

Dunno whether your colleagues have read https://moodledev.io/general/releases/3.7#Server_requirements all the way up to https://moodledev.io/general/releases/4.5#Server_requirements.

I know, nine such documents ask for a lot of memory power. That is why I summarized them in this chart: http://www.syndrega.ch/blog/#php-and-dbms-compatibility-of-major-moodle-releases. Pay attention to the "Earliest from" column to plan your route.

 

Also note the varying system software requirements - the columns min., max.

 

Moodle 4.3 - 4.5 LTS are the latest stable. For sure you need to upgrade to 4.1 LTS, which is still (security) supported, https://moodledev.io/general/releases. And immediately to 3.7.final, which is 3.7.9, which needs no effort and covers a whole series of security patches, https://docs.moodle.org/37/en/Upgrading.