Rolling back Android 9 to Android 8: safe downgrade of a smartphone

Returning to a previous version of Android is a task with which device owners face after an unsuccessful update. Android 9 Pie, despite the improved interface and new functions, it often brings problems: slowdowns, incompatibility with applications or errors in the system. Android 8 Oreo, in turn, remains a stable and proven version for many smartphone models. But how can you safely return the old firmware without turning your phone into a “brick”?

The rollback process is not just installing the old version on top of the new one. It requires unlocking the bootloader, resetting the settings and carefully working with the firmware. In this article we will analyze all stages of downgradefrom preparing the device to data recovery, and also tell you which smartphone models officially support rollback without loss of warranty (spoiler: there are less than 5%). If you are ready to take risks for the sake of stability, read on.

Why users return from Android 9 to Android 8

At first glance, a rollback seems pointless: new versions of Android bring improvements in security and performance. However, practice shows that up to 30% of users (according to forums XDA Developers and 4PDA) prefer to return to Oreo after updating. Main reasons:

• 🐢 Slowdown work: Android 9 is optimized for flagships, but on budget models (for example, Xiaomi Redmi Note 5 or Samsung Galaxy J6) it may slow down due to increased hardware requirements.
• 🔌 Battery problems: Energy saving algorithms in Pie sometimes conflict with the processor core, which leads to rapid discharge.
• 📱 Incompatibility of applications: Old versions of banking apps, games or corporate software may not run on the new one OS.
• 🔄 Interface errors: Bugs with navigation gestures, animation or display of notifications are common complaints after an upgrade.

It is important to understand that not all problems can be solved by rolling back. For example, if lags are caused by a worn-out battery or full memory, downgrading will not help. Before you act, check:

• 📊 CPU load in Settings → Battery → Usage.
• 🗃️ Free memory space (less than 10% - critical).
• 🔋 Battery status through applications like AccuBattery.

⚠️ Attention: Manufacturers rarely test downgrades for compatibility. On some models (for example Huawei P20 Lite), after a rollback, the camera or fingerprint scanner may stop working.

Preparing the device for downgrade: what to do before updating the firmware

Rolling back Android - this full system reset, so preparation takes up to 70% of success. If you skip even one step, you risk losing data or blocking your device. Let's start with the most important:

1. Data backup

Even if you plan to use cloud services Local copy is required. Android 9 and 8 use different storage structures, so:

• 📁 Copy photos, videos and documents to a PC or external drive.
• 📱 Save the list of applications via Google Play (Menu → My Apps → Library).
• 🔑 Export SMS and call log using SMS Backup & Restore.
• 📋 Write down the IMEI of the device (dial *#06#), you will need it to restore communication.

Pay special attention to:

• 🔐 Wi-Fi passwords: They can be exported through Rootapplications (for example, WiFi Password Viewer), but without superuser rights you will have to write them down manually.
• 🎮 Game saves: Many titles (for example, Genshin Impact or PUBG Mobile) are tied to the account, but local save files may be lost.

2. Checking model compatibility

Not all smartphones support downgrade. For example, Google Pixel allows you to roll back officially, but Samsung blocks the bootloader on most models. The table below shows examples of devices with varying degrees of support:

Manufacturer	Model	Possibility of rollback	Risks
Google	Pixel 2/2 XL, Pixel 3/3 XL	Officially (via Android Flash Tool)	Data loss, possible camera bugs
Xiaomi	Redmi Note 5, Mi A2	Via Fastboot or TWRP	Requires bootloader unlocking, risk of brick
Samsung	Galaxy S8, Note 8	Partially (only through Odin)	High risk of blocking KNOX
Huawei	P20, Mate 10	Closed (without official support)	Loss of warranty, possible soft-brick

To accurately determine compatibility: Find your model on the forum data-i="119">Make sure that the manufacturer does not block downgrade via

1. Find your model on the forum XDA Developers (chapter Device Forums).
2. Check if there is one for her custom recovery (For example, TWRP).
3. Make sure that the manufacturer does not block downgrading through anti-rollback (relevant for Huawei and OnePlus).

⚠️ Attention: On devices with Dynamic Partition (introduced in Android 10, but also found on some firmware Pie) rollback may lead to the loss of the partition userdataCheck the partition structure via adb shell ls /dev/block/by-name.

Unlocking the bootloader: a step you can’t do without

The bootloader (bootloader) is the “guard” of your smartphone, which controls the startup of the system. By default, it is blocked to prevent the installation of unofficial software to downgrade it. you must unlock, but this process has nuances:

• 🔓 On Google Pixel i Xiaomi unlocking is officially allowed, but resets all data.
• 🔒 On Samsung i Huawei a special key is required (for example, through the service DC-Unlocker).
• ⚠️ On some models (for example, Sony Xperia) unlocking leads to the loss of DRM keys (camera quality deteriorates).

Instructions for most devices (using an example Xiaomi):

1. Activate Developer mode: go to Settings → About phone and press 7 times on MIUI version.
2. Enable USB debugging i OEM unlocking v Settings → Advanced → For developers.
3. Connect the phone to the PC and run the command:

   adb reboot bootloader

4. In Fastboot mode, enter:

   fastboot oem unlock

   On some devices you will need to enter fastboot flashing unlock.

After unlocking, the phone will automatically reset (factory reset). Do not interrupt the process - this may lead to soft-brick (the device will turn on only in mode Fastboot).

What to do if the bootloader does not unlock?

If the command fastboot oem unlock returns an error FAILED (remote: unknown command), then the manufacturer has blocked this function Alternative. options:

1. Use utilities like Mi Unlock Tool (for Xiaomi) or Samsung Odin.

2. Contact the service center for official unlocking (for a fee, ~1500–3000 rubles).

3. exploits (for example, DirtyCOW, but this is risky).

Searching and downloading the correct firmware

An error in choosing the firmware is the main reason brick (inoperability) of the device you need exactly the same version of Android 8, which was originally installed on your smartphone. Where to look for it?

• 🌐 Official sources:
  • Google: Android Flash Tool (for Pixel).
  • Xiaomi: MIUI Downloads (choose Stable ROM).
  • Samsung: SamFW or SamMobile.
• 🛠️ Custom firmware:
  • LineageOS (based on Android 8: version 15.1).
  • Resurrection Remix or Pixel Experience (for advanced users).

How to check the firmware before installation:

1. Check device model (for example, Redmi Note 5 has options whyred and vince).
2. Make sure that the version is not newerthan the one that was originally installed (check through Settings → About phone → MIUI/Android version).
3. For Samsung it is important to match the region (CSC): for example, SER (Russia) or XXV (Europe).

Firmware files usually have extensions:

• .zip — for installation via TWRP.
• .tgz or .tar.md5 — for Odin (Samsung).
• .img — images for Fastboot.

⚠️ Attention: Firmware from websites like needrom.com or androidfilehost.com may contain modified bootloaders. Always check the MD5hash of the file (for example, through the utility HashMyFiles).

Installing Android 8: step-by-step guide for different methods

The firmware method depends on the manufacturer and model of the device. Below are the three most common methods with detailed instructions.

Method 1: Through Fastboot (for Google Pixel, Xiaomi, OnePlus)

Suitable for devices with an unlocked bootloader You will need:

• PC with installed ADB and Fastboot.
• Firmware in format .img or .zip.
• Cable USB Type-C (preferably original).

Steps:

1. Set the phone into mode Fastboot:

   adb reboot bootloader

2. Unpack the firmware and place the files in the folder with Fastboot.
3. Run the command to check the connection:

   fastboot devices

   (the serial number of the device should be displayed).

4. Flash each partition by queues:

   fastboot flash boot boot.img
   fastboot flash system system.img
   fastboot flash vendor vendor.img
   fastboot flash userdata userdata.img

5. Clear the cache:

   fastboot erase cache

6. Reboot the device:

   fastboot reboot

Method 2: Via TWRP (for custom firmware)

TWRP (Team Win Recovery Project) is an alternative recovery that allows you to install firmware without a PC. Suitable for most devices, but requires preliminary installation TWRP.

Instructions:

1. Download TWRP for your model from official website.
2. Install it via Fastboot:

   fastboot flash recovery twrp-3.6.0-whyred.img

3. Boot into TWRP: hold Power + Volume up.
4. Make a backup of the current system (Backup → Select Partitions).
5. Flash the firmware:
   • Click Install.
   • Select file .zip.
   • Confirm installation by swiping.

Clean Dalvik/ART Cache and reboot.

Method 3: Via Odin (for Samsung)

Odin —the official utility for flashing devices Samsung. It is easy to use, but has strict requirements for firmware files.

Steps:

1. Download Odin3 v3.14.4 and firmware in the format .tar.md5.
2. Run Odin as administrator.
3. Connect the phone in mode Download Mode (hold Power + Volume down + Bixby).
4. In Odin select firmware files:
   • BL — bootloader.
   • AP — system.
   • CP — modem.
   • CSC —regional settings (select HOME_CSCso as not to reset the data).

Press Start and wait for completion (the process takes 5-10 minutes).

After flashing the device automatically will reboot. The first startup may take up to 15 minutes —do not interrupt it!

Data recovery and system setup after a rollback

After a successful downgrade, you will be greeted by “clean” Android 8 - without applications, accounts and personal settings. Data recovery requires caution: not all backups are compatible with the new (old) OS version.

1. Restoring from a backup

If you used TWRP to create a backup, you can return the data like this:

1. Boot into TWRP.
2. Select Restore and specify the folder with backup.
3. Mark partitions Data and System (if necessary).
4. Confirm the restoration.

For cloud backups:

• 🔄 Google Account: contacts, calendar and some settings are synced automatically the first time you sign in.
• 📱 Samsung Cloud or Mi Cloud: restore data via Settings → Accounts → Recovery.

2. Manual file recovery

Photos, videos and documents can simply be copied back to the device. But with applications it’s more difficult:

• 📥 Install APKfiles manually (if you saved them via APK Extractor).
• 🔄 Recover application data via Titanium Backup (requires root).
• 🎮 For games, use saves linked to account Google Play Games or Facebook.

3. System setup

Android 8 has different settings than Pie. Please note:

• 🔒 Security: Enable encryption in Settings → Security → Phone encryption.
• 📶 Network: Set up APN for the mobile data (parameters depend on the operator).
• 🔋 Battery: Disable unnecessary background processes in Settings → Battery → Optimization.

⚠️ Attention: If after the rollback it stops working Google Play Services, uninstall updates for this application in Settings → Applications → Google Play Services → Three dots → Uninstall updates.

Common errors and their solutions

Even if you follow the instructions exactly, problems may arise and here are the most common ones and how to fix them:

Error	Cause	Solution
Device does not turn on (black screen)	Incorrect firmware or interrupted process	Repeat firmware, making sure the files are compatible
Stuck on the logo	Partition or cache conflict	Do wipe cache and wipe dalvik in recovery
Error DM-Verity during loading	Kernel and system mismatch	Flash disable-dm-verity-forceencrypt.zip via TWRP
Loss of IMEI or network	Partition damaged modem or EFS	Restore EFS from backup or reflash CP (modem)

If your problem is not list:

1. Check the error logs via adb logcat.
2. Look for a solution on the forums by device model (for example, 4PDA or XDA).
3. Contact the service center if you suspect a hardware fault.

What to do if the touchscreen does not work after a rollback?

This is a rare but possible problem on some models (for example, Xiaomi Redmi 4X). Reasons:

1. Incompatibility of the sensor drivers in the firmware.

2. Damage to the cable connector. disassembly.

Solutions:

- Flash another version of Android 8 (for example, Global Stable instead of China Stable).

- Check the operation of the sensor in Fastboot (if it works there, the problem is Software).

FAQ: Answers to frequently asked questions

Is it possible to roll back Android 9 to 8 without losing data?

No, downgrading always involves full reset (wipe) partition data. Even if you use HOME_CSC in Odin, some system settings will be lost. The only way to save the data is to make a full backup via TWRP or Titanium Backup (required). data-i="366">full reset root).

Will the banking application work after a rollback?

It depends on the application. Most banking apps (for example SberBank Online or Tinkoff) support Android 8, but may require an update. Google Play Services. If the application refuses to work, try:

• Install an older version of APK (for example, with APKCombo).
• Disable Play Protect in settings Google Play.
• Use Magisk to disguise root (if there is one).

How to return the warranty after unlocking the bootloader?

Technically warranty is void when unlocking the bootloader on most brands (except Google Pixel and some models XiaomiHowever, there are ways to hide traces:

• For Samsung: use Odin to flash official stock firmware with flag RELOCK (if supported).
• For Xiaomi: run the command fastboot oem lock (but this will block the bootloader again).
• For Huawei: the warranty cannot be returned - the manufacturer records the status of the bootloader on the servers.

In any case, the service center can detect traces of interference in logs or status KNOX (on Samsung).

Is it possible to roll back from Android 9 to 8 on a phone with a Snapdragon chip?

Yes, but there are nuances:

• On Qualcomm Snapdragon (for example, SDM660 on Xiaomi Mi A2) rollback is usually easier than on Mediatek or Exynos, thanks to open documentation.
• Use firmware marked SDM (for example, whyred_global_images_V10.0.2.0.OEIMIXM_20190227.0000.00_8.1_global).
• For devices with Treasury (rollback protection) a patch may be required anti-rollback.

What to do if the camera does not work after a rollback?

This is a common problem on Samsung i Huaweidevices. Reasons:

• Incompatibility of camera drivers with Android 8 version.
• Missing files libcamera in the partition vendor.

Solutions:

1. Flash the partition separately vendor from the stock firmware.
2. Install a custom kernel (for example, FrancoKernel for Pixel).
3. Use alternative camera applications (for example, GCam or Open Camera).