diff --git a/error_codes.txt b/error_codes.txt
index 67e80d5..c40f0d7 100644
--- a/error_codes.txt
+++ b/error_codes.txt
@@ -4,6 +4,7 @@
 403: login error (no cookie)
 404: invalid url / not found
 410-419: argument/data error
+420: invalid authetication object
 429: ratelimit
 
 500: server error
\ No newline at end of file