Galaxy S26 Ultra Firmware Spotted — One UI 8.5 Development Underway?

Samsung has officially kicked off firmware development for its next-generation Galaxy S26 series, several months ahead of its expected launch in early 2026. The first firmware build has already been spotted on Samsung’s test servers, signaling that internal testing is underway for the upcoming flagship lineup. The devices are likely to run Android 16-based One UI 8.5.

Galaxy S26 Ultra’s One UI firmware spotted on Samsung’s servers

X user @Koram_Akhilesh recently spotted a test firmware build for the Galaxy S26 Ultra on Samsung’s servers. The build carries firmware version S948USQU0AYG8. While that’s pretty much all we can take away from this sighting, the early appearance of the firmware is noteworthy. Samsung has begun software development for the 2026 flagships, aiming to fine-tune One UI features and enhance stability well in advance.

Rumors suggest the Galaxy S26 lineup will include three models, but not a Plus. Instead, Samsung may integrate the S26 Edge into the main lineup, sandwiched between the base S26 and S26 Ultra. This year, the Galaxy S25 Edge arrived separately, as a fourth S25 model. Note that Samsung also launches an affordable FE variant later in the year. The Galaxy S25 FE may arrive in September or October.

Based on Samsung’s recent nomenclature and this firmware discovery, the Galaxy S26 Ultra will bear the model number SM-S948. The S26 Edge should be SM-S947 (or maybe it’ll take the SM-S946 identifier typically occupied by the Plus models). The base model should be SM-S941. The FE lineup, meanwhile, falls under the SM-S7xx series. The Galaxy S25 FE is SM-S731, and the S26 FE could be SM-S741.

With firmware development already in motion, more details about the Galaxy S26 series should surface in the coming months. As mentioned, the next-gen flagships are expected to ship with One UI 8.5 based on Android 16. Samsung is yet to begin a wide rollout of One UI 8, which debuted with the Galaxy Z Fold 7, Flip 7, and Flip 7 FE. Stay tuned for more updates.