I had an interesting Office application unable to start error today on Windows 10 when the OneNote icon loaded in the notification area. When I tried to open all the other Office 365 applications installed on my computer, they all started with an updating Office loading screen, then erroring out, forcing a close.
Since OneNote was the application that first tripped this error, I thought Microsoft uninstalled the last good version of OneNote without my consent again. When this happened before, I was shocked when I saw a new interface without any of my data. The newer version of OneNote doesn't include all the features of OneNote 2016 since they are basically discontinuing the product line, or in the very least only providing a bare bones version.
It wasn't this problem again, but it did remind me to finally migrate my data away from OneNote.
Fix System Files
The first thing I tried was to attempt to find and repair missing or corrupted system files.
- Open an elevated command prompt.
DISM.exe /Online /Cleanup-image /Restorehealthand hit Enter.
- It takes a little time to update the image to fix corruptions.
- If you have Windows Update problems, type
DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:C:\RepairSource\Windows /LimitAccessand hit Enter.
- More info on fixing modern Windows Update errors (8 and up).
sfc /scannowand hit Enter.
When I finished this procedure, I updated my image (great!), but the SFC scan did not find any missing or corrupted system files. On to the next procedure.
The following 2 for commands below register every file type in a location until the end of the folder, this case it's a registered system32 directory of all DLLs. You either type these commands out or copy and paste them into an elevated command prompt.
for %i in (%windir%\system32\*.dll) do regsvr32.exe /s %iand hit Enter.
- There are quite a bit of DLL files so this may take a while. If you know which DLL needs to be re-registered just do that one manually. I find that this saves time if you don't know.
for %i in (%windir%\system32\*.ocx) do regsvr32.exe /s %iand hit Enter.
- Any IT pro knows about the pain of dealing with ActiveX controls. This one may not be necessary but there are not a whole lot of these files to run through (less than 10 on a normal install).
This re-register section did it for me. I guess there was an update somewhere that borked a few DLLs.
Office Application Unable to Start Conclusion
After the second procedure above and a quick restart later, I was able to launch all my Office 365 applications. If the first procedure didn't work for you, the second one should. If these 2 procedures did not, then follow the clean boot procedure from Microsoft to do more troubleshooting.