RSS Error – Error: could not find an RSS or ATOM feed at that URL.

Does it work for you by now ? How did you fix this ?

I have the same problem. Any luck?

I have it but not with other themes so it has to be the way the theme has been put together.

I have the error however my RSS works when I use the standard RSS url:
https://www.domain.com/feed/rss

I imagine it is a straightforward issue but surprised no one has put the fix here already!

I am having the issue too.

If I use https://domain.com/feed, it works fine
If I use https://domain.com/category/categoryname/feed, it doesn’t work and I get the error that the OP mentioned.

Please post your real URL’s.

For the error message, Error: could not find an RSS or ATOM feed at that URL. That often appears when you first use the widget. Replace the error message with the correct URL for your feed.

I found the issue. My feed was correct, but apparently it’s an outdated RSS parser within WordPress? That’s beyond me.

But what worked was updating the parser per the instructions on this topic: https://www.ads-software.com/support/topic/120458/page/2?replies=24

The instructions I followed are:

1. Download the latest magpieRSS package from here: https://magpierss.sourceforge.net

There’s a lot of files in this tarred and gzipped archive. You only need the four .inc files in the root directory.

2. Dump rss_utils.inc, rss_parse.inc, and rss_cache.inc into the wp-includes directory.

3. Near the beginning of rss_fetch.inc, change the call to Snoopy.class.inc to this:

require_once( MAGPIE_DIR . ‘class-snoopy.php’);

This will work as class-snoopy.php is already in the wp-includes directory and there’s no need to install the extlib directory.

4. Rename rss_fetch.inc to rss.php and overwrite existing rss.php file in wp-includes with the new file.