An Office 2013 non-security update, part of yesterday's massive Patch Tuesday, blanks the folder pane in Outlook 2013, the suite's email client, drawing complaints from customers on Microsoft's support forum.
Mid-day Wednesday, Microsoft acknowledged that the update was flawed, confirmed it had yanked the original and was working on re-releasing a correction, and urged users to uninstall the update.
The update, identified as KB2817630, was meant to quash a several stability and performance bugs in a number of the suite's components, including Excel, SharePoint Server and Lync; fix a problem that caused Office to freeze when a document was opened in the "Protected Mode" sandbox; and more.
Instead, it emptied Outlook 2013's folder pane.
"I can't view my list of e-mail accounts, folders, favorites, etc.," said Trevor Sullivan in a message Tuesday that kicked off a long support thread.
Scores of others quickly chimed in to say the same had happened to them after applying the update on PCs running Windows 7 or Windows 8.
"Same problem on multiple fully-updated Windows 7 Enterprise Edition, Windows 8 Enterprise Edition and Windows 8.1 Enterprise Edition workstations ... all with Office 2013 32-bit," said "MiToZ" on the same thread.
Within minutes of Sullivan's post, users reported that they'd gotten the folder pane view back after uninstalling KB2817630.
Microsoft was not available for comment late Tuesday.
However, users said that the original update had been pulled from both Windows Update and Windows Server Update Services (WSUS). The former is the patch service aimed at consumers and very small businesses, while the latter is the Microsoft-provided patch delivery and management service used by most businesses. Others reported that they'd contacted their Premier Support representatives -- a support plan available only to Microsoft's largest customers -- but had not been told when a fix would be available.
The gaffe is the latest in a series of embarrassments for Microsoft stemming from flawed updates. In August, the Redmond, Wash. company yanked an Exchange security update, saying it had not properly tested the patches. In April, Microsoft urged Windows 7 users to uninstall an update that crippled PCs with the notorious "Blue Screen of Death"; it re-released the update two weeks later.
A few users dealing with the empty folder pane bemoaned the trend.
"Yeah, another Microsoft Update Tuesday Blunder," said "Triple Helix" on the long thread.
"Someone on [Microsoft's] update testing team needs to get fired," added "The Computer Butler."
Near noon Wednesday, Microsoft published a blog post that admitted the screw-up, explained why it had happened and recommended customers do what users on the support discussion thread had already suggested: Uninstall KB2817630.
But although the company was contrite last month when it mucked up the Exchange security update -- going as far as to say "We will work very hard to regain your trust and confidence" -- Microsoft was more sanguine about the Outlook snafu. "We regret any inconvenience caused by this update," today's blog stated.
The flawed Office 2013 stability and performance update was issued yesterday alongside a 13-bulletin, 47-patch collection of security fixes that closed vulnerabilities in Windows, Internet Explorer, SharePoint, Word, Excel and Outlook.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His email address is firstname.lastname@example.org.