Thanks for the help. I checked the settings again and on the Setup - Hardware - WLED page there was nothing entered in the Debug field (it was empty). After selecting "None" the problem disappeared.

After the last update I get these messages: 2020-02-04 10:43:59.237 Error: (WLED) 'onHeartbeat' failed 'NameError':'name 'updateInterval' is not defined'. 2020-02-04 10:43:59.237 Error: (WLED) ----> Line 285 in '/home/pi/domoticz/plugins/wled/plugin.py', function onHeartbeat 2020-02-04 10:43:59.238 ...

Thanks for your hard work! The plugin works very well. It was useful to me just in time - before Christmas. Thanks again!