Windows Phone official eBay app Error – IAF token supplied is invalid. (T21916984)
IAF token supplied is invalid seems to have been an ongoing problem for eBay for Windows Phone and a few of their other official applications. eBay IAF stands for eBay Identity Assertion Framework and is used by eBay’s web servers to keep you logged in for a longer period of time than the standard login through your web browser allows.
This works by your application storing an encrypted key (code) which it receives from eBay when you sign in to eBay using the application. This key is then sent back to eBay’s server when you re-open the application and logs you in automatically so you don’t have to sign in all the time. According to Rolf (Product Manager for eBay Desktop) this key can become out of sync with eBay’s servers, especially if you don’t use the application often or make changes to your eBay account like changing your email address etc…
There doesn’t seem to be much information available about this error on line but you can see some suffering with eBay Desktop for Mac here
If you receive this error on Windows Phone 7 or Windows Phone 8, people suggest that the only current fix is uninstalling and re-installing the application (which can be a bit of a pain when you’re out and about) although, I fixed this error by signing out and back in again. On other platforms it seems more difficult it fix and if it makes you feel any better, the iPhone eBay app has suffered from this problem too. It seems like the best fix would be to catch the error and just make you log in again, which shouldn’t be hard for the developers, so I think the developers will probably fix this problem in a future release of eBay for Windows Phone.
auctionapp for Windows Phone doesn’t suffer from this problem as it uses a eBay’s auth & auth token system to request you information, make changes, bid/buy and sell on your behalf.
If you’ve had this problem and successfully fixed it on any device (or had this problem and not fixed it) please feel free to let people know in your comment.