writing to log file causes error 704

Question

Hello,

Does anyone know what this error means FATAL: Autorisation no longer valid.704

It happens when I try to write to this file, but the permissions are set to 755 and 0644 The temp folder is in the rootfolder of this subdomain.

if ($handle = fopen( 'temp/mylog.log'"a+") )
                {
    if( !fwrite( $handle, $json ) )
    {
    throw new Exception("can't write to ...");
    }
    fclose( $handle );
    }

thanks, Richard