diff --git a/Src/Notion.Client/NotionAPIErrorCode.cs b/Src/Notion.Client/NotionAPIErrorCode.cs
index 1dc822b..e0264ae 100644
--- a/Src/Notion.Client/NotionAPIErrorCode.cs
+++ b/Src/Notion.Client/NotionAPIErrorCode.cs
@@ -15,6 +15,9 @@ public enum NotionAPIErrorCode
         [EnumMember(Value = "invalid_request")]
         InvalidRequest,
 
+        [EnumMember(Value = "invalid_grant")]
+        InvalidGrant,
+
         [EnumMember(Value = "validation_error")]
         ValidationError,
 
@@ -40,6 +43,12 @@ public enum NotionAPIErrorCode
         InternalServerError,
 
         [EnumMember(Value = "service_unavailable")]
-        ServiceUnavailable
+        ServiceUnavailable,
+
+        [EnumMember(Value = "database_connection_unavailable")]
+        DatabaseConnectionUnavailable,
+
+        [EnumMember(Value = "gateway_timeout")]
+        GetewayTimeout
     }
 }