Microsoft: Zune is the only way to update WP7 phones
Microsoft has warned that an unofficial tool for updating Windows Phones will not install the most recent security update.
In a blog post on Wednesday, Windows Phone senior director Brandon Watson said the company's desktop Zune software was "the only official way to update the operating system on the phones". However, he said the creators of the unofficial tool were "a clever bunch" who "believe they have created a way to get [unofficially updated] phones back on the officially supported path", and said Microsoft would work with them to validate their tool.
Microsoft released its most recent Windows Phone 7 update, the '7392' version, on Tuesday. In his post, Watson said the company had previously warned that the unofficial updating tool would not be able to update past version 7390, and said it had proved to be the case that those who had used the unofficial tool to update to 7390 were unable to use even the official Zune tool to update those devices to 7392.
"With the official update process there is a requirement that the package on the phone also be official in order to update itself," Watson wrote. "Phones updated via the unsupported method do not contain an official image and cannot be updated further at this time. Due to scheduling of engineering resources, we did not anticipate having to undo the changes made to phones by these unsupported methods. While we are not ruling out having a fix in the future, for now there is no fix."
According to Watson, the unofficial program used undocumented APIs to force updates, resulting in an incomplete update that changed the handset, or, as he put it, the "state machine".
"When we test our update process, we test against a known state machine," Watson said. "Further, as a health protection mechanism, the phone will always try to recover from an error state (as in an incomplete update), and will begin doing things to solve for the fact that it is in an unknown state. This is the reason why phones started downloading OEM updates after forcing the update via this unofficial tool. It's also the reason why people who used the unofficial tool to get to 7390 reported that their phones later updated to 7390 via the Zune PC software.
"The state machine looked more like pre-7390 than it did 7390. However, because of the existence of some of the 7390 bits on the phone, and the fact that the 7390 update process was not intended to run against this a priori unknown state machine, the result was an incomplete 7390 update."