Exact model-family answer directory
Samsung Galaxy S21 troubleshooting
Samsung Galaxy S21 (SM-G991*): the first without a charger; what owners run into; how to approach a fault; finding your model and software; heat and the 2021 chips; charging, and a fix for each symptom below.
- The first without a chargerThe S21 was the 2021 compact flagship and the first S-series phone sold without a charger. Its chips ran warm, its battery was modest and it has now reached the end of its software support.
Samsung Galaxy S21 biometric unlock is not working
Open record Samsung · notificationsSamsung Galaxy S21 notifications are delayed or missing
Open record Samsung · speakerSamsung Galaxy S21 speaker is quiet, distorted or has no sound
Open record Samsung · Wi-FiSamsung Galaxy S21 will not connect to Wi-Fi or keeps disconnecting
Open record Samsung · BluetoothSamsung Galaxy S21 will not pair or stay connected over Bluetooth
Open recordConfirm the model first
Which units this covers, and how to tell yours is one of them
- Model numbers and patterns
- SM-G991*
Published specification
What is true of this model and changes how you fix it
- Tier — flagship base (no S Pen)The compact older flagship, no S Pen, small battery. One UI over Android, nearing end of major updates.
- AgeBattery aging and end-of-major-updates are age factors, not faults.
- What owners run intoHeat from the 2021 chips and an exhausted battery are the main complaints; owners also report cameras that stutter and a phone that no longer gets updates.
- How to approach a faultCheck Battery health, avoid heavy use while charging and restart weekly.
- Finding your model and softwareSettings, About phone shows the model number. The S21 is older and no longer receives new Android versions, so the last patch is the one to note.
- Heat and the 2021 chipsThe Snapdragon 888 and Exynos 2100 ran hot under load. Reduce screen brightness, avoid gaming while charging and take off the case when the phone is hot.
- ChargingThe S21 charges at 25 watts and shipped without a charger, so a USB Power Delivery adapter is needed. A cable that is frayed near the connector charges slowly or intermittently, and replacing it is the cheapest fix.
- Heat and the 2021 chipsThe S21 gets hot in games and while charging. Turn off 5G in poor signal, lower the screen brightness and take off the case while charging. If the phone is hot at idle with nothing running, boot into Safe mode to look for a rogue app, and consider a battery replacement.
- Storage and speedIf the S21 feels slow, clear caches in Device care, remove unused apps and keep a few gigabytes free. Turn off animations in Developer options for a snappier feel. Because the phone no longer gets updates, avoid installing heavy new apps that need recent Android versions.
Where these figures were read. samsung.com/sg/smartphones/galaxy-s21-5g/specs/ (no current US samsung.com/us spec page for this discontinued model) (flagship base, One UI)
Manufacturer support for this product line. Samsung Support — Mobile device support. Official Galaxy model manuals, diagnostics, updates and repair support.
Also read for this model. Samsung Support — Samsung Support.
Exact questions
Questions that only have an answer for the Samsung Galaxy S21
My Galaxy S21 won't get the newest One UI/Android.+
The S21 has reached or is near the end of its major-update window (Samsung provided several years of OS upgrades plus extended security updates), so it may keep getting security patches but not the newest Android/One UI version. A missing newest feature is that support age, not a fault. Check Settings › Software update; if none appears, it has reached the end of its major-version support.
Does the S21 come with a charger?+
No, it shipped without one.
Why does my S21 run hot?+
The 2021 chips ran warm and the battery has aged.
Does the S21 get new updates?+
No.
What charger does it need?+
A 25 watt USB Power Delivery adapter.