I have just upgraded to Moodle 3.9 from Moodle 3.5.17 (I've read the thread advising we don't upgrade, but only after I actually upgraded, sorry!). After the upgrade, some of the links within my site are no longer working. I cannot click the arrow near my name to log out. In the site administration, the different sections (server, appearance, etc.) also don't work. Nothing happens when I click; the link seems to change but the page does not. I am able to get around this by specifically searching for a setting and changing it from there. I initially thought this was due to the Academi theme I have installed, but it turns out it's happening with the classic theme as well. I have tried purging all caches and also accessing the site using different browsers to no avail.
I have Moodle hosted on Bluehost.
OS: Linux, PHP version: 7.2, Database server: 5.6.41-84.1 - Percona Server (GPL), Release 84.1, Revision b308619
Has anyone ever had this happen to them?