Samsung has quietly replaced its planned One UI 8.5 Beta 4 update (build ZZAB) with a newer ZZAD build currently undergoing internal testing. The last-minute switch, discovered on January 20, 2026, suggests Samsung identified critical issues with the ZZAB firmware approximately seven weeks into the beta program for Galaxy S25 users.
What Happened to Beta 4
According to Sammy Fans and beta tester Yash TarunVats, Samsung removed the ZZAB build and its changelog from test servers after initially preparing it for public rollout as Beta 4. The changelog had detailed improvements for AI Select, Bixby, the Phone app, and Bluetooth calling functionality.
The replacement ZZAD build is now undergoing internal assessment before release to beta participants. While Samsung hasn’t officially explained the switch, pulling a beta build at the last minute typically indicates discovery of critical bugs or stability issues that warranted immediate intervention.
What ZZAB Would Have Fixed
The now-canceled ZZAB build was set to address several notable issues:
Phone app problems: Search history glitches, occasional crashes, and difficulties pasting call links into the keypad
Bluetooth calling issues: Calls unexpectedly switching from Bluetooth headsets to the device speaker mid-conversation
AI Select bug: The feature remaining open after copying content instead of closing automatically
What’s New in ZZAD Build
The replacement ZZAD build introduces at least two confirmed changes:
Kernel version restored: Returns to kernel 6.6.98, reverting from whatever version ZZAB introduced. Kernel changes can affect performance, battery life, and system stability.
Direct Voicemail feature: A new addition that may function similarly to Apple’s Live Voicemail, allowing the phone to transcribe incoming voicemails in real-time or take messages on the user’s behalf.
Whether ZZAD includes all the fixes from ZZAB remains unclear, as Samsung has not released a complete changelog for the newer build.
Beta Program Timeline
The One UI 8.5 beta program is now approximately seven weeks old, running as a standalone track despite no explicit user demand for it. Samsung initiated the program to polish the software experience and apply finishing touches before the official release.
Expected rollout schedule:
- This week (late January 2026): ZZAD build expected to deploy to beta participants
- February 2026: Galaxy S26 series unveiling alongside One UI 8.5 announcement
- Mid-March 2026: Stable One UI 8.5 release for Galaxy S25
- Q2 2026: Rollout to existing Galaxy devices
Samsung will likely release additional beta builds beyond ZZAD to further refine the software before the stable launch.
Why This Matters
The build switch highlights both the risks and value of beta testing. Pulling ZZAB at the last minute prevented potentially problematic firmware from reaching thousands of beta testers, avoiding widespread issues that could have damaged user experience and delayed the stable release.
As industry analysts frequently note, beta programs are crucial for “identifying bugs and issues that developers may have missed” and “improving the product based on user feedback.” This iterative testing process aims to ensure a more stable and refined experience upon official release.
The program has reportedly progressed without significant backlash regarding update delays, suggesting Samsung’s approach of releasing multiple builds for testing is meeting participant expectations.
What Beta Testers Should Know
Galaxy S25 users enrolled in the One UI Beta Program should:
- Check device settings regularly for the incoming ZZAD update expected this week
- Monitor official Samsung channels and tech outlets like SamMobile for announcements
- Review the official changelog once Samsung releases it for ZZAD
- Report any issues encountered to help Samsung identify problems before the stable release
- Be aware that additional beta builds may arrive before the March stable launch
What We Don’t Know Yet
Several details remain unclear:
- The exact reason Samsung pulled ZZAB (critical bug? stability issue? security concern?)
- Whether ZZAD includes all ZZAB fixes or represents a complete rebuild
- Specific new features from the Galaxy S26 series that may appear in future betas
- The precise public rollout date for ZZAD this week
- How many more beta builds will arrive before the stable March release
Samsung typically doesn’t publicly explain why beta builds get pulled, focusing instead on moving forward with improved versions.
The transition from ZZAB to ZZAD demonstrates Samsung’s commitment to quality control, even when it means scrapping work at the last minute. For beta participants, this means a slightly longer wait but potentially more stable software when Beta 4 finally arrives.
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