Problem with RSS Feed

Something is very wrong with the feed: https://validator.w3.org/feed/check.cgi?url=http%3A%2F%2Fwww.der-bank-blog.de%2Fratgeber%2Ffeed%2F

Try deactivating all plugins. If that resolves the issue, reactivate each one individually until you find the cause.

If that does not resolve the issue, try switching to the Twenty Fifteen theme to rule-out a theme-specific issue (theme functions can interfere like plugins).

Thats what I did, and the Problem seems to be in conjunction with Yoat SEO and W3TC

If you clear W3TC’s cache, does the problem go away (even if only temporarily)?

No

Ok, so the problem only goes away if you disable *both* W3TC and Yoast SEO?

How about if you clear W3TC’s cache and then disable just W3TC?

Then the Problem is not there anymore

Then it must be within th esettings of W3TC

Yes, in that case, I recommend asking at https://www.ads-software.com/support/plugin/w3-total-cache#postform so the plugin’s developers and support community can help you with this.

The Problem disappears after Clearing the Cache and Comes back when you reload the rss

Clear the cache, then disable the cache, then finally deactivate W3TC.

Does the problem return when you reload the feed?

Yes, it always Comes back

Ok, this time, deactivate Yoast, then flush the cache again. Does the problem come back when you reload the feed?

yes, it it Comes back

Argh, that’s so weird.

So, just to be sure of the initial theory, please try this:

1. Deactivate Yoast SEO.

2. Clear W3TC’s cache.

3. Disable W3TC’s cache.

4. Deactivate W3TC.

5. Check the feed.

6. Reload the feed.

Does the problem come back?