Well, I started experiencing the following error recently trying to open Excel workbooks directly in the Outlook message I received it in.
Microsoft Excel cannot open or save any more documents because there is not enough available memory or disk space.
- To make more memory available, close workbooks or programs you no longer need.
- To free disk space, delete files you no longer need from the disk you are saving to.
Now, I’m running on a machine with 8+GB of free RAM, CPU running under 5%, plenty of free HD and the Excel workbook is 975kb in size, so what gives Microsoft!?
Now, I don’t know the root cause, nor do I have the time to troubleshoot yet another Microsoft blunder, but thought I’d share the easy workaround for anyone else having facing a similar issue: save the file to your PC.
Once I dragged the file to my desktop (or other folder) I was able to launch it without issue.

Similar issue for me opening files downloaded to ‘Downloads’ folder. This has not been an issue until recently and I don’t want to start changing the Trust Center settings just for a bug as it might have security implications for me in the future.
I also find that by dragging the file to another folder unblocks it.