OK, this relates to a simple Update, *not* a version Upgrade, but this seemed to be the best place to post it.
I have a site running Drupal 6.28. I've maintained it with few issues for several years. The only noteworthy feature it has is CiviCRM, which is uses a separate MySQL database anyway.
Yesterday, while attempting to make two routine module updates (the latest versions of IMCE and Views Bulk Operations), I received the following error message upon running Update.php:
An unrecoverable error has occurred. You can find the error message below. It is advised to copy it to the clipboard for reference.
Please continue to the error page
An HTTP error 0 occurred. http://www.justice4michigan.org/update.php?id=64&op=do
When I do continue to the error page, I receive the following details:
warning: array_pop() expects parameter 1 to be array, boolean given in /home/justice4michigan/public_html/update.php on line 316.
The update process was aborted prematurely while running update # in .module. All errors have been logged. You may need to check the watchdog database table manually.
When I check the error log itself, it just shows the same error as above. When I go back to view the status/updates available, it *appears* that everything has been properly updated.