I have my own domain which is hosted by a third-party and using cPanel, I have installed ownCloud 9.1.4 via the Installatron Applications Installer... As you can guess from the title above, I have also installed the ownCloud "Calendar" application, using ownCloud's own application browser.
This is a "clean" installation of ownCloud, as I had to completely remove and re-install ownCloud due to an unrelated issue (an upgrade that broke ownCloud).
The ownCloud "Files" and "Notes" applications both seem to be working, regardless of whether I am using the web-based interface or a compatible client... But when I select "Calendar", things go pear-shaped.
Essentially, all I see is a spinning circle to the left of "Personal" (i.e. my default calendar) which never goes away and in the case of Mozilla Firefox, it causes ownCloud to "freeze" within the web page (this doesn't seem to happen with Vivaldi - it just sits there with the spinning circle).
Furthermore, Mozilla Thunderbird is unable to connect to my calendar using CalDAV - it shows a padlock icon with the error message "The calendar ownCloud is momentarily not available" when you hover over it.
I have tried creating entries in the web-based interface, but these are neither saved (due to the aforementioned "freezing"), nor are they synchronized to any of my devices. The reverse is also true - entries made on my smartphone are not synchronized back to my ownCloud Calendar, despite my synchronization application ("CalDAV-Sync" by "dmfs GmbH") stating that the synchronization was successful.
Any help in correcting this issue would be appreciated.
UPDATE: The complete log from ownCloud is viewable here.