After applying December update KB3114409 for Outlook 2010, Outlook 2010 may only start in Safe Mode. Microsoft is aware of this issue and has pulled the update as a result.
A new update has been released which fixes this issue; KB3114560. You don’t need to uninstall KB3114409 first but can either install it directly by downloading the update via the KB article or via Windows Update.
In a corporate environment, you may need to wait for your administrator to approve the update on their update server (WSUS) before you’ll get the update. Contacting your corporate Support Desk may speed up this process.
Symptoms you may encounter are;
- Outlook 2010 is loaded with the default settings.
- Reading Pane is turned off.
- Modified settings aren’t being retained upon restarting Outlook.
- Add-ins are disabled.
- The Quick Access Toolbar and Ribbon have been reset and can’t be customized.
- Instant Search doesn’t work.
If you are affected by this, you can safely uninstall update KB3114409 from your computer as is doesn’t contain any security updates. After uninstalling it, restart your computer and Outlook 2010 will start normally again with your own settings. As the update has been removed from Windows Update, it will not automatically re-install.
Administrators can also deploy a Registry value to prevent Outlook 2010 from starting in Safe Mode instead of undoing the deployment of the update.