I have been getting this error every time I click on a hyperlink in an Outlook 2013 email. It has been very frustrating.
The problem was solved by resetting the HKEY_CLASSES_ROOT\.html String (Default) value to 'htmlfile'. Apparently, this was happening frequently when un-installing Google Chrome. However, on my machine it appears that Notepad++ changed the key!? I made the fix, restarted Outlook, and it works now!
I found the solution here:
Here are the steps (from the link above):
Verify that the String (Default) value of the "HKEY_CLASSES_ROOT \.html" key is "htmlfile"
- Click Start, and then click Run.
- In the Open box, type regedit, and then click OK.
- Locate, and then click the following registry subkey:
- Make sure that the value of the String (Default) is "htmlfile". If it's not "htmlfile", right-click (Default), click Modify, input htmlfile in the Value data box, and then click OK.
- Exit Registry Editor.