There is a bad news for owners of HTC Windows Phone 8X and the HTC Windows Phone 8S. Microsoft has presently put a hold on its update Windows Phone 8.1 update for the above phones. This action is applicable to Preview for Developers. Only the registered developers will be allowed this update; the non developers will have to pay $19 developer fee and can get it from Windows Phone App Studio website.
The HTC phones need to have this update with a driver that is a technical requirement for them. First it has to come from the manufacturer and only then the Developer Preview version can be delivered two HTC phones as mentioned above.
To be precise, Microsoft version is quoted below:
"There are a small set of devices for which we aren't offering the latest build of the Developer Preview program due to an identified problem that requires mobile operator or OEM driver updates. These will be offered when the official update for your phone is available."
There is another reason for this pause in sending the updates to HTC Windows Phone 8X and HTC Windows Phone 8S. Considering their market share they do not hold a prominent place; they just have 4.7% share of U.S. Windows Phone, which is not very significant. However Microsoft has decided not to deprive the owners of these two models from getting the updates, maybe via a Developer Preview.