If you have new users (that’s right—new) trying to create a new YouTube channel and then running into errors…

… like this…

… or like this.

Lots of people have run into this issue, and there many proposed guesses (but no consensus) as to what’s the issue and what’s the fix:
My Channel and Create Channel are stuck in Infinite Redirect Loop!
Youtube Login Redirect Loop Error
Fix a “redirect loop” on youtube?

I can’t say the following procedure will always fix the problem, but the one time I ran into this issue, this was the fix that worked.

Click on your profile picture on the top-right, then click the gear icon to go to YouTube settings.

Then, click on Advanced.

Then click Delete channel.

Authenticate.

Check I understand that the following will be permanently deleted and can’t be restored and then click Delete channel.

Confirm you want to delete the channel by clicking Delete channel.

Keep in mind once you delete a YouTube channel, Google won’t let you delete another one for a long while (there doesn’t seem to be an agreed-upon amount of time before you can delete again—I’ve read anywhere between a week and a month), so choose your YouTube channel name wisely!