     }
 
     vTaskSuspend( x_dimmerTaskHandle );
-    for ( byte channelNumber = 0; channelNumber < NUMBER_OF_CHANNELS; channelNumber++ )
+    for ( uint8_t channelNumber = 0; channelNumber < NUMBER_OF_CHANNELS; channelNumber++ )
     {
       channel[channelNumber].currentPercentage = 0;
       ledcWrite( channelNumber, 0 );

    }

    vTaskSuspend( x_dimmerTaskHandle );
    for ( byte channelNumber = 0; channelNumber < NUMBER_OF_CHANNELS; channelNumber++ )
    {
      channel[channelNumber].currentPercentage = 100;
      ledcWrite( channelNumber, ledcMaxValue );

    // https://stackoverflow.com/questions/8323159/how-to-convert-uint64-t-value-in-const-char-string
    // cardsize = uint64_t
    // length of 2**64 - 1, +1 for nul.
    char content[21];
    snprintf( content, sizeof( content ), "%" PRIu64, SD.cardSize() );
    server.send( 200,  textPlainHeader, content );
  });

  server.on( "/api/files", []()
