Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/MicroDexed/src/commit/2900b031a98318275e050e6fd9c7c4bc937fdf13/third-party/ArduinoJson/examples/JsonGeneratorExample You should set ROOT_URL correctly, otherwise the web may not work correctly.