1.5.1 RSS .92 not working

I updated the code to 1.5.1, and applied the fix from;
https://fernando.dubtribe.com/archives/2005/05/10/solution-to-wp151-rss-errors/

and I get errors-
not on the 2.0 but on the .92 I get this;
XML Parsing Error: undefined entity
Location: https://vanbos.com/?feed=rss
Line Number 27, Column 17:

should I worry about this as the 2.0 works or is there a fix for this?

Thanks!