Your ROOT_URL in app.ini is https://src.whiteboxsystems.nl/ but you are visiting http://src.whiteboxsystems.nl/Whitebox/u-boot/src/commit/ddd960e6c4b8412fa5c5a35f36cc3ac9f3ffbc16/configs/P1020RDB_NAND_defconfig
You should set ROOT_URL correctly, otherwise the web may not work correctly.