The roll out of Windows Phone 7.8 has been slow, but users have managed to get their hands on the lucrative update. However, it would appear they could be in for a nasty surprise in exchange for that pretty new Start screen due to a newly discovered bug with the update's Live Tiles.
The initial discovery was made a week ago by Heathcliff74, one of the prominent developers behind Windows Phone's homebrew scene who brought us the Interop Unlock and the ability to run native code in unsigned apps. Apparently, there is a crippling bug in the way Windows Phone 7.8 updates its live tiles.
There was one app in particular he discovered, Tweakers.net, which attempted to refresh the image on its live tile repeatedly from a web address that no longer existed. Instead of realizing the address was a dud, Heathcliff says the OS kept trying to communicate with the website repeatedly. The resulting damage was a huge amount of data used by the tile — over 600 MB in the span of a few hours — and a rapidly drained battery.
Heathcliff74's contributions have made him a credible source of any information regarding Windows Phone's inner-workings, but when he first reported about the problem he was facing with the Live Tiles in 7.8 we chose not to write about it assuming it could have been an isolated issue. Since then however, other sites are reporting that he's not alone in his issues with Windows Phone 7.8's live tiles.
After a week of testing, Heathcliff has returned with new results on his blog, suggesting this is a bug on the operating system level. Of the three methods developers can choose to update a live tile, two have proven to be buggy or outright broken. The first method is known as Shell Tile Scheduler, which is the same procedure that was used by the Tweakers.net app to retrieve a URL and display the updated image on the tile. The second method is known as HTTP Notification Channel which follows a similar procedure as the previous method but instead goes through Microsoft's own Notification Servers. Speaking about the latter method, Heathcliff says it is "completely broken" and was shocked to find it even made it past quality assurance testing.
How to Avoid It
What may be most concerning about this bug is how difficult it is to discover or avoid. The problem is that not all apps that use the Shell Tile Scheduler method mentioned above exhibit this bug. Heathcliff recommends being wary of live tiles that are 'flickering' while pinned to your Start screen, saying its a sign of the app repeatedly attempting to update. If you see an app doing this, it's best to unpin it immediately to avoid high data usage and a not-so-nice bill from your operator. One example is the Bing Translator app for Windows Phone, which he says is affected by the issue in 7.8.
If you're a developer with any useful info regarding the issue, Heathcliff is looking for any kind of help he can get (follow him on Twitter here). More importantly, Microsoft absolutely needs to see this and figure out if it's something they can fix on their side. In the meantime, keep a close eye on your Start Screen and your data usage and please let us know if you spot any apps with this issues for others to avoid.
Source: WP7 Root Tools