Hi, I've just tried to upgrade a site from 7.15 to 7.16 and have encountered an odd problem.
I upgraded the site by running 'drush up' as usual, but after completing the upgrade I immediately got a white screen of death with the error below when trying to access the admin pages:
Fatal error: Class 'DrupalQueue' not found in modules/update/update.fetch.inc on line 246
Disabling the update module in case that was the problem led to:
Fatal error: Class 'DrupalQueue' not found in [path-to]/public_html/includes/common.inc on line 5141
Thinking that the database had got corrupted somehow I restored to a backup I took before upgrading, but the problem still persisted. After that I decided to see whether the problem was with the way drush performed the update, so I downloaded a fresh version of .16 and overwrote the site files. Nope, still a problem.
After much googling with no real answer, I reverted back to the old .15 files and restored the database to the backup again. Everything running smoothly.
As a test, I ran drush up one last time - even though there were no database updates the problem returned. This time there was no white screen of doom, but the 'Fatal error' text was printed very small at the bottom of every page. Again, rolling back to .15 sorted it out.
Do you know what the problem may be or have you had anything similar happen? It seems I'm stuck on .15 for now.
I'm on a CentOS server, running PHP 5.2.17 and MySQL 5.1.65