For those of you who use the Google Custom Search Engine, like we do here, you may have noticed that it is having issues reading your XML Sitemap file. Yes, with a Google CSE (custom search engine), you can feed it your pages, like you do with normal web search, with your Sitemap file.
If you do that now, you may see an error that reads:
Oops! We were not able to retrieve a list of Sitemaps associated with your current Google account.
A Google Custom Search Help thread has confirmation of the bug. Googler, Prathap Reddy, explained that this is indeed a bug, but it is only a display bug and has no impact on your Google Custom Search Engine.
We are aware of listing of sitemaps is not working in Control panel. We are working on that issue.
The issue is basically a cosmetic issue and shouldn't affect the functionality of Google Site Search in any way.
You can submit the sitemap for on-demand indexing by entering the URL in sitemap URL text box in Google Site Search Control panel -> Indexing Tab.
So do not panic, the display issue should have no impact on the functionality of your Google CSE. Plus, the display issue should be resolved sooner than later.
Forum discussion at Google Custom Search Help.