KiCAD 8.0 on Windows 10 64-bit.
I open the project via the project file (so I know the project is not missing) and try to edit schematic or layout properties, and am met with this error.
I’ve searched around and saw this could be an issue with Windows file/directory permissions or Dropbox interactions.
I’ve copied the project folder from Dropbox and quit dropbox but the problem persists even with this new copy.
I check in Windows explorer and confirm the files are not marked read only. I checked every single file property and none are marked as read only.
Should I just update to 9.0 and see if it’s resolved?
Update: I moved the folder to my Desktop, opened the project and did a Save As back to the original directory.
Then opened the new project, and there are no access/permissions issues so far. No clue what the issue is. Will re-open Dropbox and see if that somehow causes issues.
Thanks for your note. I had the exact same problem (using KiCad 9.0) until I tried your solution and it worked. I use Dropbox but I tried solving the problem with and without Dropbox running and that made no difference. After using your “Save As” method, the problem went away and now works even while Dropbox is running. So, this particular problem may not be related to Dropbox.