This month I have done a maintenance release of PodcastUtilities. I was seeing this error from a number of sites, including the BBC, The Guardian and NZ Tech Podcast.
GetFeedEpisodes: warning, unable to add an episode for Tech Weekly, Thu, 03 Dec 2015 15:35:14 UTC is not a valid RFC 822 string representation of a date and time.
I was surprised by the error as it looked OK to me. I ended up adding another unit test with this string in it and when I debugged it I was surprised to discover that the error is correct, the date is not valid. According to RFC 822 the only legal suffixes for universal time are GMT, UT or Z (see page 26), UTC is not valid. I didn't really know what to do in the end I decided to be pragmatic and permit the invalid date format as it was obvious that it was supposed to be UT. It is a bit alarming that big internet providers don't appear to be able to support the simplest standards, and somewhat alarmingly some weeks they were find and on others it was invalid.