Asus doesn't have the best track record for updating its phones, but it was really making an effort earlier this year with it rolled out an Android 9 beta for the Zenfone 4. Unfortunately, Asus' resolve has faded, and there won't be a final Pie update. It says the Zenfone 4 will continue to get Oreo maintenance updates. You know... if you still believe Asus.
Asus released the Zenfone 4 almost exactly two years ago with Android 7.1 Nougat. It later got an update to Android 8 Oreo, and Asus promised at least one more system upgrade. It rolled out a Pie beta in June of this year, and that was the last we heard until today. Asus now says that in order to "preserve the system performance and stability," it won't update the Zenfone 4 to Pie.
Zenfone 4 owners on the Asus forums are predictably upset by the change of plans. Asus notes that users can still download and install the Pie beta, but that's an odd consolation. It's unfinished software and won't get any update support.