Microsoft Outlook Error Code: 0X8004010d

Microsoft Outlook will throw out an error that reads

An unknown error occurred, error code: 0x8004010d.

I was able to generate this error when I was trying to mount a PST file. The problem ended up being that there was very little to no free disk space available on the same volume as the PST. Once I cleared up some space, I was able to add the PST with no additional problems.

If you're having problems deleting files because they are in use, you can follow this guide on figuring out which processes are using files.