Your ROOT_URL in app.ini is https://source.parasitstudio.de:63000/ but you are visiting https://source.parasitstudio.de/wirtz/uClock/src/commit/f6d36e76aae124c739490bbc1c2d8aae2835bd9e/examples/TeensyUsbMasterMidiClock You should set ROOT_URL correctly, otherwise the web may not work correctly.