Creating a backup copy is a basic skill that saves you from data loss when your smartphone breaks down or files are accidentally deleted. However, when it comes time to restore information or simply view the contents of an archive, users often encounter incomprehensible file extensions. The file backup android is not a regular document or image, so you won’t be able to open it by double-clicking through standard Windows Explorer. The system simply does not know which app to process this specific container.
The problem is aggravated by the fact that different tools create archives in completely different formats. The copy made via ADB will be different from the file created by Titanium Backup or Google's built-in feature. To successfully extract data from a backup copyyou must first accurately determine the type of archive. In this article, we will look in detail at how to identify the file format and what utilities can be used to safely unpack the contents without damaging the data structure.
The process of restoring or viewing files requires caution and the right choice of software. The wrong app may distort the data or refuse to work with the archive altogether. Let's look at the main scenarios for working with backups and the tools that will become your main assistants in this matter.
Identifying the backup file type
The first step before attempting to open an archive is to determine its format. Often files are created without an extension or have a standard name backup.ab, backup.tar or simply data. The file extension in the Windows operating system may be hidden by default, so you need to enable the display of extensions in the Explorer settings. This is a critical point, since the decryption method directly depends on the type of container.
The most common format created by a standard command line utility ADBis .ab (Android Backup). This format is a specific wrapper that can contain encrypted or unencrypted data in tar format. If you see a file with the extension .ab, standard archivers like WinRAR or 7-Zip will not be able to open it directly without first converting it.
Another popular type is .tar or .tar.gz. Such files are often created by custom recovery, such as TWRP, or specialized applications with superuser rights. The Tar format is the de facto standard for creating full partition images in the Linux environment on which Android is based. Opening such a file is the easiest, but the folder structure inside may be unusual for a Windows user.
- 📂 .ab — native Android backup format that requires conversion for viewing on a PC.
- 💾 .tar /.tar.gz — standard archive, often used in custom recovery and root utilities.
- 💿 .vmdk or .img —full disk images created during system cloning or emulation.
⚠️ Warning: Never try to rename a file extension manually (for example, change .ab to .zip) if you are not sure of the data structure. This will lead to the fact that the archiver will not be able to correctly read the file headers and will display an archive corruption error.
Working with the .ab format through conversion utilities
Files with the extension .ab are created by the command adb backup and are the most difficult to view directly on a computer. Inside such a container, the data is packaged in tar format, but the container itself has an Android-specific header structure. To access the files, you must first "pull" the internal tarball. For this, there are several proven tools that work both through the graphical interface and through the command line.
One of the most reliable ways is to use the utility abe (Android Backup Extractor). This is a app written in Java that allows you to convert .ab to .tar and back. The conversion process requires an installed environment Java Runtime Environment on your computer. After installing Java, just run the utility jar file and drag your backup file into the app window.
If you prefer to work with the command line or use a server version of the OS without a graphical interface, you can perform the conversion manually. To do this, use the following command, which extracts data starting from the 24th byte of the file (skipping the Android-specific header):
dd if=backup.ab bs=1 skip=24 | openssl zlib -d > backup.tarAfter executing this command, you will receive a file backup.tarthat can be opened with any standard archiver. It is important to understand that if the backup was created with encryption (password), then without knowing this password, it will not be possible to decrypt the contents even after conversion. The encryption algorithm in Android is quite strong, and guessing the password can take years.
Before converting, always create a copy of the original .ab file. If the process is interrupted or goes wrong, you will have the original archive to try again.
Opening TAR and GZ archives from custom recovery
Users who have installed custom recovery, such as TWRP or OrangeFoxusually work with format files .tar or compressed .tar.gz. These archives are created by the "Backup" function in the recovery menu and contain sector-by-sector copies of system partitions (Boot, System, Data, Cache). You can open them on a computer to view individual files (for example, photos or contacts) using standard tools, but the structure inside will be specific.
The apps 7-Zip or WinRARare ideal for unpacking such files on Windows. After installing one of these utilities, just right-click on the backup file and select "Open archive". You will see folders with section names, for example, data, system, boot. The user data you are interested in is usually located in the folder data/media/0 (internal memory) or data/data (application data).
However, it is worth considering the nuance with access rights. Symbolic links and Linux-specific permissions may be stored inside the archive, which do not make sense in a Windows environment. When unpacking, some files may not be extracted correctly if the archiver does not support these attributes. In this case, it is recommended to use the "Extract all" option with the "Maintain access rights" checkbox if your archiver supports it.
| app | Format support | Difficulty of use | Platform |
|---|---|---|---|
| 7-Zip | tar, gz, zip, ab (after conversion) | Low | Windows, Linux |
| WinRAR | tar, rar, gz, zip | Low | Windows, macOS |
| Android Backup Extractor | ab (conversion to tar) | Medium | Cross-platform (Java) |
| TAR (Linux/Mac) | tar, gz, bz2 | High (CLI) | Linux, macOS |
☑️ Check before unpacking TAR
Access to application data and encrypted partitions
The most difficult part of working with backups is accessing application-specific data, especially if it is encrypted. Modern versions of Android (6.0 and above) use Full Disk Encryption (FDE) or File-Based Encryption (FBE). This means that even if you unpack the partition image data, you will not be able to read the files inside without the decryption key, which is tied to the lock screen of your device.
Working with such data often requires the use of specialized software to emulate the Android environment on a PC. apps like Android Studio Emulator or ready-made images in the format .vmdk can be connected as a virtual disk. If you have a full system image (img), you can mount it into a virtual machine, but to decrypt the data you will still need to enter the PIN code or pattern that was used on the original smartphone.
If we are talking about backups from applications like Titanium Backup (require root), then the data is stored in the form of a pair of files: application_name.apk and application_name.tar.gz (or.properties). To restore such data, it is best to use the Titanium Backup application itself on an already configured smartphone with superuser rights. Trying to manually unpack these archives on a PC often results in loss of permissions metadata, making the apps inoperable once returned to the phone.
⚠️ Attention: Interfaces and Methods encryption in Android is updated regularly. What worked for Android 9 may not be applicable for Android 14. Always check the relevance of decryption methods in the official documentation of the developers of the tools you use.
Cryptographic keys are stored in a protected area of the processor (TrustZone) and are not exported along with data files.
What to do if you forgot the password for an encrypted one backup?
Unfortunately, if your Android backup was encrypted when it was created and you forgot the password, it is almost impossible to recover the data. The AES encryption algorithms used in Android have no backdoors. The only chance is to remember the password or try simple combinations if they were used. Third-party services that promise hacking are most often fraudulent.
Using emulators to mount images
If your backup is a full disk image (files .img, .vmdk, .qcow2), standard archivers are powerless here. Such files are created for complete cloning of a device or for working in emulators. To access the content, you must mount the image as a virtual disk. In the Windows environment, you can use the built-in disk management function or third-party utilities for this, such as OSFMount or WinCDEmu.
The mounting process is as follows: you run the app, select the image file and assign a free drive letter to it. After this, the image appears in “My Computer” as a regular flash drive or hard drive. However, the file system inside the image may be ext4 or f2fswhich Windows does not read natively. In this case, additional drivers will be required, for example Ext2Fsd or Linux Reader from DiskInternals.
After installing the file system drivers, you will be able to mount folders inside the mounted image. This is a convenient way to pull out photos, documents and downloads if your phone is broken and won't turn on, but you have a fresh, full backup. At the same time, it is not recommended to touch system files, since changing their structure may violate the integrity of the image if you plan to write it back somewhere.
To work with full disk images (.img.vmdk), be sure to use Linux file system drivers (ext4/f2fs), since Windows does not see them by default.
Typical errors when unpacking and their solution
Even with the right software, users often encounter errors when opening backups. The most common problem is the "File is damaged" or "Unknown format" message. Most often, this means that the file was not completely downloaded or the backup process was interrupted on the smartphone. Check the checksum of the file (MD5 or SHA1), if it was provided when creating the backup, and compare it with the amount of the file on the computer.
Another common error occurs when you try to open a file created in a newer version of Android on older software. For example, the utility Android Backup Extractor may not support new compression methods introduced in Android 12 or 13. In such cases, you need to update Java to the latest version and download the current build of the utility. It is also worth checking whether the archive uses proprietary compression, which is not supported by open source software.
If, when unpacking, you receive access rights errors for individual files inside the archive, try running the archiver as an administrator. Sometimes this helps to correctly process file attributes transferred from a Linux environment. As a last resort, you can use a virtual machine with Linux (for example, Ubuntu), where working with such archives is native and does not require additional crutches.
- ❌ CRC error — the file is damaged when writing or downloading, you need to copy it again.
- 🔒 Access error — try running the app as an administrator or using Linux.
- 📉 Insufficient space — to unpack you need free space that exceeds the archive size by at least 1.5 times.
Is it possible to open backup Android on the phone itself without a computer?
Yes, this is possible, but with limitations. If you have a .zip or .tar file, you can use archive-enabled file managers such as ZArchiver or RAR, directly on your smartphone. However, .ab files or full system images will require root access and specific terminal commands, which is difficult for the average user. The easiest way to restore a backup is through the same application that created it (for example, through Google settings or Titanium Backup).
What is the difference between a full backup and a partial one?
Full Backup contains a copy of all memory partitions: the system partition, bootloader, user data and cache. Its size can reach tens of gigabytes. A partial backup includes only selected data: contacts, SMS, photos or settings for specific applications. Full backups are used to completely restore the system after a failure, and partial backups are used to transfer data to a new device.
Is it safe to open backups on someone else’s computer?
Opening backups on someone else’s computer is risky if they contain confidential information (passwords, correspondence, photos). Even if you do not restore data, but only view the archive, traces of temporary files may remain on someone else’s PC. It is recommended to use portable versions of archivers from a flash drive and after work securely delete temporary files using the “File Shredder” function.
Why does the archiver write that the file is multi-volume?
Some backup apps split large archives into parts (volumes) of 2 GB or 4 GB for compatibility with FAT32 file systems. If you have files with names like backup.tar, backup.tar.z01, backup.tar.z02, you need to put them all in one folder and open only the first file (without numbers or with the .tar extension). The archiver will automatically pick up the remaining parts.
How to recover data if the phone does not turn on?
If the phone does not turn on, but you have a backup file on your computer, the only way is to use a new or repaired phone. You cannot “download” a backup to a non-working device. You need to set up a new device, install the same applications and use the restore function from a previously created copy (via Google Account or by manually copying files from the unpacked archive to the internal memory of the new device).