Invalid characters in XML Atom feed

Question

The issue popped again as I initially reported here: issue #15320 Stack Overflow - Other

Consequence was that Thunderbird was unable to load the feed, until the invalid characters slid out of the RSS.

The error that popped on this feed because of this post is now gone but here is the error reported by the W3C validator:

Sorry This feed does not validate.

line 206, column 1357: XML parsing error: <unknown>:206:1357: reference to invalid character number [help]

    ... /p&gt;&#xA;&lt;pre&gt;&lt;code&gt;&#xA0;&#x13; &#xA;&lt;/code&gt;&lt;/pr ...
                                                 ^

If you run the W3C validator today, it sill reports an issue with the namespace:

This feed is valid, but 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://purl.org/atompub/rank/1.0 [help]

    <feed xmlns="http://www.w3.org/2005/Atom" xmlns:creativeCommons="http://backend.userland.com/creativeCommonsRssModule" xmlns:re="http://purl.org/atompub/rank/1.0">

Post that caused the invalid characters in the RSS feed:

---

Related references

• Similar status-completed issue: Invalid XML in Atom feed
• Problematic post: GDB unable to jump to specified address location [closed]
• Stack Enterprise issue tracker: issue #15320 Stack Overflow - Other

Answer 1

Our community team was doing some triaged ticket cleanup and flagged this post for me. I fixed this! ...two years ago! I have no memory of doing it, but I can confirm that it happened. Let me know if there are still any XML-related issues, but I (apparently) added in a method to strip invalid XML characters so it should be all good. Thanks for the report and sorry for the lack of update!