What does this message from Twitch mean?

I've been watching Twitch lately, but today this message comes up:

but i don't know what it is or why it is there

This means that the content no longer exists because it was deleted.

So if you want to see him, you'd have to go back in time.

It's a joke by those, the content has been deleted and you would need a time machine to travel back in time to see the content again.

But that happens in the middle of the live stream

Not available any more).

https://archive.org/web/ this is what comes closest to a time machine.

Then some content was removed from the live stream.

Yes, but it happens during the live stream without me clicking anything

Yes, then the stream was just removed.

Dear question question21

Unfortunately, the previous answers were only partially correct.

In fact, as already mentioned, this message comes with content that has already been deleted. However, even if you have entered a generally invalid link (e.g. A channel that does not exist and has never existed).

This joke by the Twitch developers alludes to the fact that either things have been deleted (journey into the past → time machine) or do not exist at the current point in time (time machine → future).

If you get this error, you likely have:

Got an old or invalid link
Clicked on a deleted medium
Clicked you when entering the url

Use the Twitch search to find certain channels anyway and check whether a typo has crept in.

To supplement it would be that this message can also appear if Twitch has problems in the backend websites, it has been even more frequent lately.

Twitch seems to have a problem again.

https://status.twitch.tv/

If not (anymore), look at the other answers.