Samsung Said to Have Begun Testing One UI 8 on Galaxy Z Fold 4 and Galaxy Z Flip 4

Samsung released its Android 16-based One UI 8 operating system (OS) at Galaxy Unpacked 2025 earlier this month. While only the Galaxy Z Fold 7, Galaxy Z Flip 7, and Galaxy Z Flip 7 FE run on the OS out-of-the-box, a tipster suggests that internal testing of the firmware for two older Galaxy devices has begun. Internal test builds of the firmware are said to have been spotted on the server for the Samsung Galaxy Z Fold 4 and the Galaxy Z Flip 4.

One UI 8 for Galaxy Z Fold 4 and Galaxy Z Flip 4

This information comes from tipster Tarun Vats’ post on X (formerly Twitter). The tipster spotted One UI 8’s internal test build on Samsung’s server which was officially listed as a “newfound test firmware”. It is said to come with the build version F936BXXUAIG3 for the Galaxy Z Fold 4 and F721BXXUAIG3 for the Galaxy Z Flip 4.

Notably, this discovery builds upon recent sightings of the One UI 8 test build for two more Samsung smartphones — the Galaxy A55 5G and the Galaxy S24 FE. Samsung is reported to have begun the internal testing of One UI 8 in May, starting with the flagship Galaxy S25 series.

However, merely the listing on Samsung server does not reveal any timeline of One UI 8’s release, although it does indicate the development of the firmware for the aforementioned Galaxy models.

Currently, only the Samsung Galaxy Z Fold 7, Galaxy Z Flip 7, and Galaxy Z Flip 7 FE are powered by One UI 8. Other smartphones in the South Korean tech conglomerate’s portfolio still run on One UI 7 which is based on Android 15.

Before the update is publicly released, those interested in trying out new features can sign up for Samsung’s One UI 8 Beta programme. This allows developers and beta testers to experience the Android 16-based OS and tailor their apps to run adeptly. This programme is available in 36 countries including India, the US, and South Korea.