WindowsSteamBlog: "Despite the fact that many people have claimed that an unofficial update mechanism worked fine for them, we cautioned that phones which were updated via this method were not going to be able to update past build 7390. Unfortunately for those customers out there who acted on information from sources outside of Microsoft, the rubber meets the road today.
With Windows Phone update build 7392 going out to phones via the official update mechanism, those people who have used the unsupported method of forcing 7390 onto their phones will find that their phones will not update 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.
Phones updated via the unsupported method do not contain an official image and cannot be updated further at this time."