I've started work on Adaptable for Moodle 3.9, and I really need to know what 'exactly' is broken in terms of Moodle 3.9 specifically. Thus on a test server only, install the 'master' branch from https://gitlab.com/jezhops/moodle-theme_adaptable and check that the issue has not already been raised here: https://gitlab.com/jezhops/moodle-theme_adaptable/-/issues. You must also have 'developer level' debugging on in order to get 'stack traces' for posting here.
Therefore please post any issue you find on this thread ONLY. If you could also list the steps to replicate the problem, then that would be really helpful and assist me to replicate the issue faster.