The Activity Log shows a critical entry like:
core: invalid URL received: https://www.googleapis.com/youtube/v3/videoCategories?part=snippet&id=10&key=...
Jamroom was asked to load an address from another site, and the address isn't valid.
Look at the address in the message:
& instead of &: the address was HTML-encoded somewhere, often when it was pasted into a setting. Enter it again with plain &.https://, or a typo: correct the setting or template the address came from.The entry's details in the Activity Log show the page it happened on, which helps find where the address comes from.