I encouter around three errors a day in my DNN 5.6 site!
These errors are caused by Googles Mobile Adsbot!

I tried to add several lines in the .browser files, but none of theme seem to work!

This is the ID of Google's AdBot:

AdsBot-Google-Mobile (+http://www.google.com/mobile/adsbot.html) Mozilla (iPhone; U; CPU iPhone OS 3 0 like Mac OS X) AppleWebKit (KHTML, like Gecko).

This was the last entry I tried in the OceanSpiders.browser file:

<browser id="GooglebotMobile" parentID="docomon505i">
  <identification>
   <userAgent match="AdsBot-Google-Mobile" />
  </identification>
  <capture></capture>
  <capabilities>
   <capability name="crawler" value="true" />
   <capability name="browser" value="Googlebot-Mobile-Ads" />
   <capability name="version" value="3" />
   <capability name="majorversion" value="3" />
   <capability name="minorversion" value="0" />
   <capability name="crawler" value="true" />
   <capability name="isMobileDevice" value="false" />
  </capabilities>
 </browser>

Maybe the regex isn't working? I tested it with some online regex testers and there was no problem!