Microsoft pulled an Office for Mac 2011 major update from its upgrade servers on April 20, acknowledging bugs that have corrupted the Outlook database on some machines.
Office for Mac 2011 Service Pack 2 (SP2) was released April 12. That same day, users who had upgraded began reporting problems on Microsoft's support site, saying that they were unable to run Outlook, the suite's email client.
On April 17, Microsoft confirmed that the SP2 upgrade could in some cases corrupt the Outlook identity database, and offered workarounds to prevent that from happening for those who had not yet installed the service pack, as well as a step-by-step guide to reconstructing the database for those affected by the bug.
Three days later, Microsoft took more drastic action, shutting down the delivery of Office for Mac 2011 SP2 through the company's automatic upgrade service.
"Our goal is provide the simplest update experience for everyone -- so we have temporarily stopped pushing out the SP2 update through Microsoft AutoUpdate while we investigate the issue," Microsoft announced in a post on April 20 to its Office for Mac blog.
The company did not say when it would restore SP2 to the automatic upgrade channel, but did tell users they were free to manually download the service pack from its website.
Microsoft has yanked updates from its servers before. The most serious examples in recent years were in February 2010 when it stopped serving a security update to Windows XP PCs that were crashing with the notorious "Blue Screen of Death," and two years earlier, when Microsoft shut down an update for Windows Vista that crippled systems with endless reboots.
Office for Mac 2011 debuted in October 2010, and is available in two editions for the general public, as well as others for academic and enterprise customers.
Microsoft shipped the first service pack for Office for Mac 2011 just over a year ago.