There are epic threads on the internet of users upgrading to Office 2016 and finding that Outlook 2016 email is no longer indexing. Windows Search logs the following error in Event Viewer:
The protocol handler Mapi16 cannot be loaded. Error description: (HRESULT : 0x80004005).
I've tried ALL the common suspects:
- Rebuild Index
- Reinstall Office
- Remove and Re-add Outlook from Index Sources
- Remove and Re-add Outlook Profile
- We're already running Office 2016 x32
Removing Outlook from the index and using Unindexed search is acceptable as a very short term fix, but I need the "The protocol handler Mapi16 cannot be loaded." error fixed permanently.
At present this is happening on approx 50% of the workstations we upgrade to Office 2016 (Click-to-Run) and they're all running Win10 with all patches.
Best Answer
I've been struggling with the very same problem for the past few days.
It turns out it was related to the "HKCU\Software\Classes\VirtualStore" branch of the registry. It contained a few entries in the "MACHINE\SOFTWARE\Microsoft\Office\ClickToRun" subtree, so it was hiding the real "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun" subtree.
After removing the whole "HKCU\Software\Classes\VirtualStore\MACHINE" subtree and restarting the "Windows Search" service, the error disappeared and the indexing started working again.
This is the site that helped me in finding the solution : https://www.win-10-forum.de/office/87414-outlook-2016-office-365-betriebssystem-momentan-ausfuehren-anwendung-konfi.html