JSON) ', JSON_ ERROR_ CTRL_ CHAR = > ' Control character error, possibly incorrectly encoded',. json_ last_ error_ msg — Returns the error string of the last json_ encode( ) or json_ decode( ) call. Return Values ¶. Returns the error message on success, " No error" if no error has occurred, or FALSE on failure. int json_ last_ error ( void ). 直近の JSON エンコード/ デコード処理中に発生 したエラー ( もし存在すれば) を返します。. While this can obviously change between versions, the current error codes are as follows: 0 = JSON_ ERROR_ NONE.