I recently got a new MacBook and when I open my files it won’t let me save them. I get this message: “The operation couldn’t be completed. Problem writing file (Rialto Sans.glyphs.sb-fe4d2ce0-iEXokh): Permission denied.” But I have Read & Write permissions set in the Get Info box.
Where is the file stored? In a cloud storage like Dropbox or iCloud Drive?
As a test, can you save a copy of the file to the Desktop? File → Save As… (⇧⌘S).
Did you check the permissions of the file or of the folder containing the file? Both need to allow writing.
Save As to the desktop worked. Then I created a new folder in my Applications folder to put it in. When I reopened the file in Glyphs it now allows me to make changes and save it. Thank you!
You should not store files in the Applications folder. Use Documents or a folder in your User folder.