I experience this issue so often and when it occurs I should logout and login to solve it.
It's very annoying every time I got this error message I should close all my working windows.
Following messages are from my system log.
12. 9. 22. 오전 1:24:02.656 Espionage[536]: ERROR (-[NSData(TECrypto) decrypt:]:131): scryptdec_buf returned: 9
12. 9. 22. 오전 1:24:02.656 Espionage[536]: ERROR (+[DBSubdb subdbWithData:master:pass:error:]:45): failed because: !decrypted
Please find cause and fix it permanently.