HTTP error 0 upon simple module update

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.

When I check the watchdog database table via phpMyAdmin, it isn't helpful, as it just shows essentially the same error message: A PHP error:

Message:  %message in %file on line %line.

Variables: a:4:{s:6:"%error";s:7:"warning";s:8:"%message";s:58:"array_pop() expects parameter 1 to be array, boolean given";s:5:"%file";s:45:"/home/justice4michigan/public_html/update.php";s:5:"%line";i:316;}

Severity: 3

Location: http://www.justice4michigan.org/update.php?op=results

Referrer: http://justice4michigan.org/update.php?op=start&id=64

The site itself seems to be running smoothly otherwise, but I'm understandably concerned about this error showing up whenever I try to run Update.php.

Note that I have over 60 other Drupal 6.28 sites running on the same server, all of which also had IMCE updated yesterday, none of which had any issues. The only differences I can think of worth noting with this site are 1) it's the only one running CiviCRM and 2) it's the only one on which I tried to update Views Bulk Operations.

Any suggestions/advice appreciated.