I fixed it!
The whole time, I have been able to create, edit and delete files within my temp directory. However, when I looked at the security permissions, I could see that "Everyone" did not have permissions for "Full Control", "Modify" and "Read & Execute".
I ticked these boxes, got a protesting pop-up complaining that a file inside was in use, I kept clicking retry and permissions were changed. Joplin now works correctly again. I still have no idea why and how the permissions were changed in the first place.
If you are having this issue, do the following:
- go to
C:\Users\USER NAME\AppData\Local\
- find the "Temp" folder
- right click on it
- click "properties"
- inside the "properties" window, go to the "security" tab.
- Grant full permissions to your user.
- click OK
- if Joplin is running, exit Joplin ( you may need to open the task manager, find the "Joplin" processes, right click and choose "end task")
- launch Joplin
Now Joplin should work again!