Visvanath Ratnaweera

This is a general question. Let's take an upgrade from 3.9 LTS to 3.11 as an example.

Say, the 3.9 LTS was running on PHP 7.2. The march shows that PHP 7.3 not good enough for Moodle 3.11. It needs PHP 7.3-8.0.

Still you can upgrade the code to Moodle 3.11. When you try to run it, Moodle detects the new version (the old version was recorded in the database) and takes you to the upgrade script. But the upgrade script of 3.11 will detect the insufficient PHP and refuse to upgrade. Nothing breaks - unless you are one of those clever people who change the code to bypass this test. :-?

Now you upgrade the PHP to anything 7.3-8.0 and retry. This time you can continue with the upgrade.

Note that this game could be played because "Earliest from" column for 3.11 shows 3.6 (or newer).

Ref. http://www.syndrega.ch/blog/#php-and-dbms-compatibility-of-major-moodle-releases

I understood that you send your site from https://example.com/ to http://example.com/ (no 's') and back. There are a couple of things necessary for that, config.php is one of them. See the full thing under Transitioning to HTTPS. One of them is the "replace" script I mentioned.

In other words, you need to do the full thing as in the document, not half things!