Problem in latest.rss / Not a Valid Feed, it says!

[elijah (Eli the Bearded)]

Those are fairly minor errors in the RSS.

This feed does not validate.
line 7, column 19: language must be an ISO-639 language code: fa_IR [help]

      <language>fa_IR</language>

I believe the correct code is fa-ir with a hyphen not an underscore. I think this is the only one that might cause problems.

line 9, column 98: Self reference doesn’t match document location

You gave the validator an https: URL and the page there said that it is an http: resource. Super minor.

In addition, interoperability with the widest range of feed readers could be improved by implementing the following recommendations.

line 2, column 0: Use of unknown namespace: http://www.discourse.org/

That validator isn’t familiar with Discourse specifics. Not a big deal.