Galaxy S25 Problems: One UI 9 Battery Drain, Setup Bug & Fixes

One percent every 15 minutes, with the screen off. That’s how Galaxy S25 owners have been measuring their battery since One UI 9 arrived, and it’s the biggest of the Galaxy S25 problems reported since the Android 17 update landed in early October 2026. Behind it come a setup screen that won’t finish and shows an XML “Access Denied” error, plus heat and lag.

US carrier S25 models got One UI 9 on 3 October 2026, and unlocked models followed on 5 October (our One UI 9 rollout tracker has the dates for other regions). Within days a thread in Samsung’s US Community titled “[Galaxy S25+] My battery is draining after updating to One UI 9” ran to several pages.

Every Galaxy S25 model uses the Snapdragon 8 Elite for Galaxy worldwide, so unlike older Exynos/Snapdragon generations, these reports don’t split by chip.

What the drain looks like in Samsung’s forum

People in that Samsung Community thread describe roughly 1% gone every 15 minutes while idle, about 20% used by half an hour of basic browsing, and an S25 Ultra that went from 30–40% at night to single digits by morning. Several of them point at spikes from One UI Home and other system processes. Cybernews says the idle-drain reports cover both the Galaxy S24 and S25 after One UI 9.

Two things are going on. After a major update the phone re-optimises apps, rebuilds its search index and syncs cloud data. Sammy Fans, cited by Cybernews, says this optimisation can take about two weeks. Separately, a system process stuck in a loop, or a third-party app that isn’t ready for Android 17, can keep the processor awake.

Working through the battery fixes

1. Restart and update. Settings › Software update › Download and install. Update apps in both Galaxy Store and Google Play.
2. See what’s using it. Settings › Battery › View details shows usage since the last full charge. Note any app or system service near the top that you barely touched.
3. Restrict it. Tap the app › Battery › Optimised or Restricted. Apps you never need running in the background can go into Sleeping or Deep sleeping apps under Settings › Battery › Background usage limits.
4. Switch off what you don’t use. Always On Display, the high refresh rate (Settings › Display › Motion smoothness › Standard), and Nearby device scanning and Bluetooth scanning under Location services.
5. Clear One UI Home’s cache if it shows up high in the list: Settings › Apps › One UI Home › Storage › Clear cache.
6. Reset network settings if “Mobile network” is a big consumer: Settings › General management › Reset › Reset mobile network settings (or Reset network settings).
7. Reset app preferences in Settings › Apps › ⋮ › Reset app preferences. Nothing is deleted.
8. Test in Safe Mode (steps below). If the drain stops there, a third-party app is behind it.

None of this is guaranteed. Several people in the thread say cache clears and restrictions did nothing for them. If the drain is still bad two weeks after updating, run Samsung Members › Support › Diagnostics › Battery status and contact Samsung. Cybernews reports that one S24 Ultra owner was told to book a service appointment.

Stuck on setup with XML “Access Denied”

This one stops the phone dead. Sammy Fans reported on 12 October 2026 that some Galaxy S26, S25 and S24 phones, and some foldables, get stuck on the setup screen after the One UI 9 reboot. Instead of the Home Screen, they show an XML “Access Denied” error.

According to Cybernews, Samsung acknowledged a setup problem on its South Korean forum and said it happens when an unstable Android System WebView is used on certain networks. The things that have worked for users, and what Samsung suggested:

• Take the phone offline. Switch off the Wi-Fi router or pull the SIM for a while, then carry on with setup without internet.
• Force restart by holding Volume Down and Power together until it reboots.
• Use Safe Mode. Boot into it, turn off Wi-Fi and mobile data, then restart normally.
• Change network. Samsung suggested moving from mobile data to Wi-Fi, signing in to a Samsung account, and updating Android System WebView from Google Play as soon as you can.
• Leave it and try again. Some users say a restart later on fixed it by itself.

Safe Mode on the S25, step by step

Safe Mode runs the phone with only Samsung’s preinstalled apps. If drain, heat or crashes stop there, you’ve found that a third-party app is to blame.

1. Hold the side key and Volume Down to open the power menu (or swipe down twice and tap the power icon).
2. Touch and hold Power off until the Safe mode icon appears.
3. Tap Safe mode. The words “Safe mode” appear at the bottom of the screen.
4. Use the phone for a few hours. If the problem has gone, uninstall recently added apps one at a time.
5. Restart normally to leave Safe Mode.

Warm phone, stutter and crashing apps

Heat during light browsing, or while sitting on the charger, turns up in the same thread alongside the drain. Optimisation itself makes heat, so give it a few days after the update. Then:

• Check Settings › Battery › View details for an app that keeps the phone awake.
• Take the case off when fast charging, and don’t game on the charger.
• Pick Light in Settings › Device care › Performance profile if you don’t need maximum performance.
• Run Samsung Members › Diagnostics to test the battery and sensors.

For lag and app glitches, update apps first. Google Messages problems were reported in the thread, and app updates usually follow quickly. Clear a misbehaving app’s cache in Settings › Apps › [app] › Storage › Clear cache, and keep at least 15% storage free (Settings › Device care › Storage).

If the whole system stays sluggish, wipe the cache partition. Power off, connect a USB-C cable to a computer, hold Volume Up and Power to enter Recovery, and choose Wipe cache partition. Personal data isn’t touched. The last resort is a factory reset in Settings › General management › Reset › Factory data reset, after backing up with Smart Switch or Samsung Cloud.

A phone that stays hot while idle for more than two weeks, or shows a temperature warning, needs Samsung to look at it.

Buying a used S25 or S25+

With the S26 out, plenty of S25 and S25+ units are being resold. The software problems above can be fixed. A blacklisted IMEI, an unpaid finance plan or a hidden screen replacement can’t.

• Check the model number in Settings › About phone.
• Make sure the battery and screen pass Samsung Members diagnostics.
• Run a Verificação de blacklist GSMA on the IMEI.

Not sure which model to go for? Our used Galaxy buying guide compares them.

When to book Samsung service

Stop troubleshooting and book a repair if any of these is true:

• Battery diagnostics report a weak battery, or the drain carries on after a factory reset.
• The phone overheats in Safe Mode with nothing running.
• Samsung Members diagnostics fail a test (charging, sensors, touch screen).
• It keeps restarting by itself after a reset.

Samsung’s standard warranty covers manufacturing defects but not drops or liquid damage. Before you go, a Samsung Info report pulls the model, region and warranty dates from the IMEI, and our page on Samsung IMEI and warranty checks shows how to read it.