     {
       if ( !xOledTaskHandle )
       {
-        return request->send( 501, textHtmlHeader, "Not present." );
-      }
-      response = request->beginResponseStream( textHtmlHeader );
+        return request->send( 501, HTML_HEADER, NOT_PRESENT_ERROR_501 );
+      }
+      response = request->beginResponseStream( HTML_HEADER );
       response->printf( "%i", oledContrast );
       return request->send( response );
     }

    AsyncResponseStream *response;
    if ( request->hasArg( "boottime" ) )
    {
      return request->send( 200, textHtmlHeader, asctime( localtime( &systemStart.tv_sec ) ) );
    }

    else if ( request->hasArg( "channelcolors" ) )
    {
      response = request->beginResponseStream( textHtmlHeader );
      for ( uint8_t channelNumber = 0; channelNumber < NUMBER_OF_CHANNELS; channelNumber++ )
      {
        response->printf( "%s\n", channel[channelNumber].color );

    if ( !fs.exists( path ) )
    {
      path = request->arg( "filename" ) + " not found.";
      return request->send( 404, HTML_HEADER, path );
    }
    fs.remove( path );
    path = request->arg( "filename" ) + " deleted.";
    request->send( 200, HTML_HEADER, path );
  });

  server.on( "/api/getdevice", HTTP_GET, []( AsyncWebServerRequest * request)
