I have database updates to run. But when I click "Apply Pending Updates," it just sends me back to the first screen of the update workflow, though the page loads with no theming. If I click "Continue" to run it again, it goes back to the page with the "Apply Pending Updates" button (with no theming), and if I click that button again, I am redirected to my homepage, and maintenance mode is now turned on. But it doesn’t actually perform the update.
If I then try to run update.php again, I see that the same updates still need to be performed.
There are no errors in the Drupal log, or the PHP error log, so I’m not sure how to debug.