There are varying reports about whether or not HTC's recent models, the HTC One M8, One M9 and One M+, will receive the upcoming Android 6.0 Marshmallow update. However, company executives had confirmed that all of them will get the said upgrade. Owners of the two-year-old HTC One M7 may not expect the same, as it will only be upgraded to the current Android 5.1.1 Lollipop OS. 

The Taiwan-based device maker's 2015 flagships, the HTC One M9 and One M9+ are both slated to get the much awaited Android 6.0 OS. HTC's Senior Global Online Communications Manager Jeff Gordon confirmed the news via his official Twitter account a few months ago.

Prior to an Android Marshmallow upgrade, the One M9 is also being treated with version 5.1.1. Mo Versi, HTC's Vice President for Product Management, mentioned last month that HTC One M9 owners under Version will soon receive the firmware update be upgraded. Other carriers are expected to follow suit. The new OS will carry over the needed fix for the dangerous Stagefright bug along with network roaming support for 4G LTE bands 3 and 7.

While both 2015 and 2014 flagships are on the waiting list for the latest Android OS version, the company's first HTC One model released back in 2013 may not enjoy the same fate. Nevertheless, it is still in line to receive the Android 5.1.1 Lollipop as all four major U.S. carriers are reportedly preparing for an over-the-air (OTA) roll out.

Both contract-based and unlocked versions of the HTC One M7 from Sprint, T-Mobile, and Verizon are bound to get version 5.1.1 Lollipop OTA. It appears that the update for One M7 variant from AT&T has already begun rolling out earlier this month.

HTC's last generation One M8 flagship has been previously doubted whether it will get an Android M refresh. However, users of the device can rest assured as Versi also provided confirmation that it will indeed get the new OS. The HTC US chief had given a positive reply to Twitter user who asked him directly if his HTC One M8 will ever get an Android M upgrade.

Once the Android 6.0 OS comes to the HTC One M8, it will reportedly tag the HTC Sense 7 UI along. The HTC Sense is the company's proprietary user interface software placed on top of the stock Android OS from Google to make its devices' performance smoother.

It is widely believed that the consumer version of the new Android Marshmallow OS will first be offered via Google's 2015 Nexus models, the LG Nexus 5 and Huawei Nexus. After that, devices from other manufacturers, including HTC, will then distribute the said OS to their own flagship models.

On Friday, Google has started giving out invitations to the press for its September 29 launch event in San Francisco. It is the venue when the search giant is expected to unveil the abovementioned Nexus handsets along with a new Google Chromecast.