Creating a thumbnails file on Android: a complete guide with solutions for all cases

Files thumbnails are miniature versions of images and videos that Android generates automatically to speed up gallery loading. But sometimes they become damaged, are not updated, or disappear altogether after resetting the settings, clearing the cache, or installing custom firmware. As a result, the gallery shows empty icons instead of previews, and the search for the desired file turns into a lottery.

Many users mistakenly believe that thumbnails is just a cache that can be safely deleted. In fact, these files are stored in a hidden folder .thumbnails and play a key role in the operation of standard and third-party galleries. Their absence not only slows down media viewing, but can also lead to crashes in applications like Google Photos or QuickPic. In this article, we will look at how to manually create or restore thumbnails on any Android device - from older versions to Android 14.

The problem is complicated by the fact that starting from Android 10 Google has tightened the rules for access to system folders. Now, working with .thumbnails often requires root access or ADB commands. But even without them, there are workarounds - from using specialized utilities to forcing the re-creation of thumbnails through hidden settings. We will look at all the methods, starting with the simplest ones.

It is important to understand: thumbnails files are not backup copies of the original media. They contain only thumbnail copies for preview purposes, and their deletion does not affect the photo or video itself. However, their absence can seriously ruin the user experience - especially if you have thousands of files in the gallery.

What are thumbnails and why do they disappear

Files thumbnails (thumbnails) are compressed versions of images and videos that Android generates for quick display in the gallery. They are stored in a hidden system folder:

• 📁 /sdcard/DCIM/.thumbnails — for most devices
• 📁 /storage/emulated/0/DCIM/.thumbnails — alternative path on new versions of Android
• 📁 /data/data/com.android.providers.media/thumbnails — system storage (requires root)

Main causes of disappearance or damage thumbnails:

• 🧹 Clearing the application cache Gallery or Media storage (com.android.providers.media)
• 🔄 Updating or resetting Android to factory settings
• 🛠️ Installing custom firmware (for example, LineageOS)
• 📱 Transferring files between devices without saving metadata
• 🚫 Virus software that damages system folders

On devices with Android 11+ access to the folder .thumbnails is limited due to policies Scoped Storage. The system automatically restores thumbnails when you first open the gallery, but this process can take hours if there are a lot of media files. Sometimes it does not start at all due to service failures. mediaserver.

⚠️ Attention: On some devices (for example, Xiaomi with a shell MIUI) folder .thumbnails may be named .thumbdata or hidden deeper in the system partition. Before manipulations, check the free space - generating thumbnails for 10,000 photos can take up to 500 MB.

Method 1: Forced re-creation of thumbnails via settings

The easiest way is to force Android to regenerate thumbnails automatically. This method works on most devices without root access and does not require connecting to a PC.

Instructions:

1. Open Settings → Applications.
2. Find the application Gallery (or Google Photosif you use it).
3. Go in Storage → Clear cache.
4. Go back to the main application settings and click Stop (Force Stop).
5. Open the gallery and wait until the scan is completed (may take up to 30 minutes).

If the thumbnails do not appear:

• 🔄 Reboot your device.
• 📵 Turn off Wi-Fi/mobile data for 5 minutes, then turn it on again (sometimes it helps to reset the process mediaserver).
• 📁 Check if the folder is hidden DCIM (for example, after connecting to a PC in MTP).

On devices Samsung with a shell One UI an additional step may be required:

Settings → Device care → Memory → Clear now → Select "Multimedia"

⚠️ Attention: On some firmware (for example, ColorOS from Oppo/Realme) cleaning gallery cache leads to the deletion of not only thumbnails, but also user albums. Before proceeding, export important collections.

Method 2: Manual creation of thumbnails via ADB (without root)

If the standard method did not work, you can force the generation of thumbnails via ADB (Android Debug Bridge). requires superuser rights, but requires USB debugging.

Step-by-step guide:

1. Enable Mode Developer (click on Build number 7 times in the phone settings).
2. Activate USB debugging in the developer menu.
3. Connect your phone to the PC and confirm the trusted device.
4. Open the command line (Windows) or terminal (macOS/Linux) and enter:

   adb shell am broadcast -a android.intent.action.MEDIA_SCANNER_SCAN_FILE -d file:///storage/emulated/0/DCIM/

5. To fully scan all partitions, use:

   adb shell am broadcast -a android.intent.action.MEDIA_MOUNTED -d file:///storage/emulated/0/

After executing the commands, wait until the process completes (you can track it in the logs via adb logcat | grep mediaserverOn devices with Android 12+ An additional command may be required to reset the media provider:

adb shell pm clear com.android.providers.media

This method is effective if:

• 📱 Thumbnails do not appear after transferring files from another device.
• 🔄 Gallery shows empty previews after OS update.
• 🚫 The folder .thumbnails exists, but the files in it have zero size.

Method 3: Restoring thumbnails using third-party utilities

If manual methods did not help, you can use specialized applications. They work on two principles:

1. Regeneration — forced creation of new thumbnails.
2. Recovery — search for damaged files .thumb and their repair.

Top 3 applications for work c thumbnails:

Application	Functions	Requires root?	Link
Thumbnail Rebuilder	Recreates thumbnails for images and videos, supports batch processing	No	Google Play
Rescan Media	Forced scanning of media files, fixes problems with metadata	No	Google Play
SD Maid	Cleaning and restoring system caches, including .thumbnails	For deep cleaning - yes	Google Play
Mixplorer	Manual file management .thumb, support for hidden folders	No	4PDA/XDA

Instructions for Thumbnail Rebuilder:

1. Install the application and provide access to the storage.
2. Select folders for scanning (it is recommended to start with DCIM and Pictures).
3. Click Rebuild Thumbnails and wait until it is completed.
4. Restart the gallery.

For devices with MIUI or EMUI you may need to disable battery optimization for the application, otherwise the process will be interrupted. You can do this in the settings:

Battery → Battery optimization → Select application → No restrictions

Method 4: Manually creating thumbnails files (for advanced users)

If automatic methods do not work, you can create files .thumb manually. This method requires access to the file system and basic knowledge of the structure of thumbnails.

Thumbnail file formats:

• 🖼️ .thumbdata3- — for images (JPG, PNG)
• 🎥 .thumbdata4- — for video
• 📄 thumbnails_idx — index file (stores links between originals and thumbnails)

Action algorithm:

1. Connect the phone to the PC in MTP (or use a file manager with root access).
2. Go to the folder /sdcard/DCIM/ and create a hidden folder .thumbnails (if it is not there).
3. Download file templates .thumbdata for your version of Android (can be found on XDA Developers or 4PDA).
4. Place them in a folder and set the rights 755 (rwxr-xr-x).
5. Restart the device and wait for the automatic generation of thumbnails.

For devices with Android 11+ you may need to use Termux to change rights:

termux-setup-storage
cd /sdcard/DCIM/.thumbnails
chmod 755 .thumbdata3*
chmod 755 .thumbdata4*

⚠️ Attention: Incorrect file editing .thumbdata can lead to complete loss of previews in the gallery. Before manipulation, make a backup copy of the folder .thumbnails.

What to do if .thumbdata files are damaged?

Corrupted thumbnail files can be recognized by their zero size or .thumbdata3-bak extension. In this case, you need to delete them and then restart the service. media scanner command adb shell am broadcast -a android.intent.action.BOOT_COMPLETED.

Method 5: Restoring thumbnails after resetting

After hard reset or flashing the files .thumbnails are deleted along with other system data: You can restore them in two ways:

Method 1: From a backup

• 🔄 If you have a backup via Titanium Backup or Swift Backup, restore the application data com.android.providers.media.
• 📁 Copy the saved folder .thumbnails back to DCIM (root is required to restore rights).

Method 2: Through cloud services

• ☁️ If you use Google Photos, enable the option Save originals on the device in the synchronization settings.
• 🔄 After downloading the files, thumbnails will be generated automatically (may take up to a day).

For devices Samsung with function Samsung Cloud:

1. Go to Settings → Accounts and Backup → Samsung Cloud.
2. Restore data Galleries from the latest backup.
3. Confirm synchronization and wait for completion (thumbnails will be restored along with metadata).

If there are no backups, the only way out is to wait for automatic generation. On devices with Android 9 and below, this process can be speeded up by temporarily disabling battery optimization. for the service mediaserver:

adb shell dumpsys deviceidle whitelist +com.android.providers.media

Solving problems with thumbnails on custom firmware

On unofficial firmware (for example, LineageOS, Pixel Experience) problems with thumbnails are more common due to:

• 🔧 Incorrect access rights to system folders.
• 📦 Lack of a pre-installed media provider.
• 🔄 Conflicts between GApps and standard services.

Instructions for LineageOS:

1. Install the latest version Open GApps (minimum package nano).
2. In TWRP execute cleaning:

   Wipe → Advanced Wipe → Select "Cache" and "Dalvik Cache"

3. Reboot and wait for the first boot (may take up to 15 minutes).
4. Install Simple Gallery or Aves —they work better with custom firmware.

For firmware based on Android 12+ manual configuration may be required SELinux:

adb shell setenforce 0
adb shell restorecon -Rv /data/media/0/DCIM/.thumbnails
adb shell setenforce 1

If thumbnails still do not appear:

• 📌 Check the error log via adb logcat | grep -i thumbnail.
• 🔄 Try an alternative gallery (for example, F-Stop or QuickPic).
• 📥 Install the module Magisk MediaProvider Fix (available in the repository Kitsune Mask).

⚠️ Attention: On some custom firmware (for example, Havoc-OS), the folder .thumbnails may be located in /data/media/0/Pictures/. Before manipulation, check the current path through a file manager with root access.

FAQ: Frequently asked questions about thumbnails on Android

❓ Why do thumbnails appear only for new photos, while old ones remain empty?

This is a typical problem after transferring files from another device or memory card. Android generates thumbnails only for media that has been scanned by the system. Solution:

1. Delete the folder .thumbnails manually.
2. Use Rescan Media to force scanning.
3. Check if old files are hidden (sometimes they are marked as system files).

❓ Is it possible to transfer thumbnails from one phone to different?

Technically yes, but it makes no sense. Files .thumbdata are tied to:

• The specific version of Android.
• Media storage paths on the device.
• Hash sums original files.

When transferring, the thumbnails will not match the new paths, and the gallery will simply re-create them again. The exception is clones of one device (for example, when replacing the motherboard).

❓ Why do thumbnails take up so much space?

On devices with resolution screen 1440p Android generates thumbnails in high quality (up to 512×512 px). To save space:

• Use SD Maid to clear old ones .thumbdata.
• Disable the generation of thumbnails for videos (in the settings of some galleries).
• Install the module Magisk Thumbnail Quality Modifier.

❓ How to restore thumbnails after deleting the DCIM folder?

If you deleted the folder DCIM together with .thumbnails, but the original media files remained in others directories:

1. Restore the folder structure (DCIM/Camera, DCIM/Screenshots).
2. Move the files back (the names must match!).
3. Run the command:

   adb shell am broadcast -a android.intent.action.MEDIA_SCANNER_SCAN_FILE -d file:///storage/emulated/0/DCIM/

If the files have been permanently deleted, the thumbnails cannot be restored - they will have to be generated again.

❓ Why does Google Photos show thumbnails, but the standard gallery does not?

This happens due to different scanning mechanisms:

• Google Photos uses cloud cache and its own database of thumbnails.
• Standard the gallery relies on local files .thumbdata.

Solution:

1. Clear the cache Google Photos and the standard gallery.
2. Disable synchronization in Google Photos for 10 minutes, then turn it on again.
3. Check if the service is disabled com.android.providers.media in application settings.