If you have a Galaxy Watch 4 Classic, you might want to wait before updating to One UI 8 Watch. What was supposed to be a fresh lease on life for Samsung’s 2021 fan-favorite smartwatch is causing problems for some users.

One user shared on the Samsung Community forum that after the update, the watch no longer recognizes when it’s on a wrist (via SamMobile). Since wrist detection fails, important health features like ECG and body composition (BIA) can’t be used.

The security side is also frustrating. If you use a PIN, the watch keeps locking itself because it thinks you’ve taken it off.

Oddly, the user discovered that placing the watch face on the inside of the wrist — the palm side — sometimes tricked the sensors into working. Sadly, common fixes like clearing the cache have not solved the problem.

It’s not just the sensors acting up. Some users on Reddit say the One UI 8 Watch update drains the Galaxy Watch 4’s battery and stops Samsung’s watch faces from loading. The Always On Display also reportedly stops working after the update.

In fairness to Samsung, keeping four-year-old devices running is tough in the world of wearables. The Galaxy Watch 4 Classic remains a fan favorite because of its physical rotating bezel. The One UI 8 Watch update was supposed to help these watches stay useful for another year, but updating older hardware with new software is always risky. Here, it seems the older sensors didn’t handle the update well.

If you haven’t updated yet, it’s best to wait. Forum complaints have probably reached Samsung, and reports say the update rollout has been halted in some regions. We’ve asked Samsung for a comment and will update this article when they respond.