PassEntry uses conventional HTTP response codes to indicate the success or failure of an API request. In general: Codes in the 2xx range indicate success. Codes in the 4xx range indicate an error that failed given the information provided (e.g., a required parameter was omitted, syntax error, etc.). Codes in the 5xx range indicate an error with PassEntry’s servers (these are rare). Some 4xx errors include text that briefly explains the error reported.