I vaguely remember seeing this error in some old versions of MS Outlook many years ago in my previous IT Support workplace, so was a bit surprised when a customer from Oxford emailed me a screenshot above saying that it was popping up when trying to open any link in the latest version of MS Office 365 after a Windows 10 update.

After connecting to the affected computer via TeamViewer everything became clear – the user was running Microsoft Outlook 2010 despite having a full Office 365 license… This error is normally caused by some issue with the default web browser. In this particular case, Windows 10 installed an update which also upgraded Microsoft Edge (the default browser). All I had to do to fix the issue was open Microsoft Edge and go through a couple of welcome / setup screens. After restarting the Edge and MS Outlook, the error went away.

Obviously, all this was not strictly necessary as we immediately removed Microsoft Office 2010 and installed the latest version of MS Office 365.