Ok, usually, I'll get this type of error after I've attempted to modify an xsl for the newsfeed.  The MS XSL parser is very unforgiving when it comes to XSL structure.  Since, you don't say what kind of updating you were doing, what newsfeed URL you are using, or how your site is setup, it's difficult to say exactly what will fix your issue.  But, start with this 'fix'.

Replace whatever xsl you are using in your news module with the standard default DNN xsl.  If you've modified that xsl, then you will need to copy one from somewhere and replace it.  If you've made a change to the default xsl, then renamed it, and are using that one for this troublesome news module, then, simply copy the default dnn xsl and rename it to the name you are using in the module as the xsl source.  You should be able to get it going with one of those tactics.  It may not look good, but it will give you a way to access the module again through the site.

The other thing worth mentioning is come up with a standard workflow for placing changes into your site to avoid production situations.  I know the value of this method, because in my experience I've done everything wrong at least 5 or ten thousand times myself.  Rushing to get it done always gives me another reason to follow my workflow.  Test new xsl with a xsl editor, lots around, even if you have to pay for one.  A simple test is to merely bring it into vs to edit.  More sophisticated tools exist and are worth checking out if you are going to do much with xsl.  Then, I check the xsl with a feed in a test setup thouroughly, before using in production.  This may already be your approach, but I'm relaying the info for others, as well, just to  give some advice.

Let us know how it goes. BTW - I'm going on vacation, so I may not be much help beyond this post for about 10 days or so, so good luck.

Cheers