A week ago Microsoft promised to report back on the 80188309 issue which is stopping some Windows Phone 8 users from upgrading to the WP8.1 developer preview.
True to their word (unlike the Xbox Music people) they have now reported back on the findings of their investigation.
Eli A. , Microsoft Forum Moderator, wrote on April 24, 2014:
Thank you all for waiting patiently over the last week, and continuing to stick with us as we work on getting you the Windows Phone 8.1 Preview. We believe we have identified the fix and will be going through some of our normal testing to confirm. With that being said, I don’t have an update yet on when we will roll this fix out to you.
I plan to provide more information on Thursday May 1st. In the meantime, please continue to hold on and thank you again for your willingness to participate in our Developer Preview Program.
So it appears a solution has been found, which means it should not be long before a few million more Windows Phone 8 users can join the rest of us on WP8.1.