Image Thumbnails Not Showing on Windows: Fixes
Why Windows Stops Showing Image Thumbnails
You open a folder full of photos and instead of seeing small previews of each image, every file shows the same generic icon — a white rectangle with a colored border. This is one of the most common Windows annoyances, and it happens across Windows 10 and Windows 11 alike. The frustrating part is that it rarely has a single cause. Sometimes a system update resets a thumbnail setting. Sometimes the thumbnail cache — a hidden database Windows maintains at C:\Users\[YourName]\AppData\Local\Microsoft\Windows\Explorer — gets corrupted or bloated past the point where Windows can read it reliably. Other times, the problem is a folder-view setting that got toggled off, or a Group Policy restriction on a work or school machine that explicitly disables previews. There are also format-specific failures: Windows has never natively supported thumbnails for certain file types like HEIC (Apple's iPhone photo format), WebP images older than Windows 10 build 1809, or RAW files from cameras unless you install the appropriate codec. Before you spend an hour chasing the wrong fix, it helps to narrow down whether the problem affects all images in every folder, only specific formats, or only certain locations like a network drive or an external hard drive. That distinction will save you a lot of time.
The Fastest Fix: Check Your Folder View Settings
The single most common cause of missing thumbnails is a View setting that Windows quietly changes — sometimes after an update, sometimes when you switch a folder to a different layout. Open File Explorer and navigate to the folder where thumbnails are missing. Click the View menu at the top. In Windows 11, this is the ribbon button labeled 'View'; in Windows 10, it's a tab. Make sure you're not in List, Details, or Small Icons view — none of those show thumbnails regardless of any other setting. Switch to Medium Icons, Large Icons, or Extra Large Icons. If thumbnails appear immediately, you're done. If they still don't appear, go one level deeper. In Windows 10, click View > Options > Change folder and search options. In Windows 11, click the three-dot menu > Options. In the Folder Options dialog that opens, click the View tab. Look for a checkbox labeled 'Always show icons, never thumbnails.' If that box is checked, uncheck it and click Apply. This single checkbox is responsible for a huge percentage of thumbnail complaints on forums. While you're in that same dialog, also make sure 'Show thumbnails instead of icons' is not blocked — on some machines the wording differs slightly. Click OK, close File Explorer, and reopen the folder. In most cases, thumbnails will start generating within a few seconds, especially if the folder contains JPEG or PNG files.
Clear the Thumbnail Cache
If the folder view settings look correct but thumbnails still aren't showing, a corrupted thumbnail cache is the likely culprit. Windows stores cached thumbnails in a set of database files inside C:\Users\[YourName]\AppData\Local\Microsoft\Windows\Explorer. These files are named things like thumbcache_32.db, thumbcache_96.db, thumbcache_256.db, and so on — each one stores thumbnails at a different resolution. When these files get corrupted or grow too large (it's not unusual to see the cache exceed 500 MB on a machine that handles a lot of photos), Windows can fail silently and just show generic icons instead. The cleanest way to clear the cache is through Disk Cleanup. Press the Windows key, type 'Disk Cleanup,' and open it. Select your C: drive, let it scan, then check the box for 'Thumbnails' in the list. Click OK and confirm. This deletes all the thumbcache_*.db files safely. Windows will rebuild them automatically the next time you browse image folders — the first browse of a large folder will be slightly slower than usual as it regenerates previews, but after that everything returns to normal. If Disk Cleanup doesn't solve it, you can delete the files manually: close File Explorer entirely (use Task Manager to end the explorer.exe process if needed), navigate to the AppData folder path above, delete the thumbcache_*.db files, then restart explorer.exe. Do not delete iconcache.db — that's a separate file for application icons and touching it can cause other display problems.
Fix Thumbnails for Specific Formats: HEIC, WebP, and RAW
If thumbnails work for your JPEG and PNG files but not for HEIC, WebP, or RAW files, the problem isn't a Windows setting — it's a missing codec. Windows doesn't include native support for every image format, and thumbnails depend entirely on the codec being present. For HEIC files (common on iPhones and iPads), you need the HEVC Video Extensions and HEIF Image Extensions from the Microsoft Store. Search for 'HEIF Image Extensions' in the Microsoft Store app and install the free version. After installation, restart File Explorer and HEIC thumbnails should appear. Note that on some Windows 10 versions, Microsoft charges a small fee (around $0.99) for the HEVC codec; the HEIF Image Extensions themselves are free. For WebP, Windows 10 version 1809 and later supports WebP thumbnails natively, so if you're on a recent build and still not seeing them, clearing the cache (as described in the previous section) usually resolves it. For RAW files — CR2 from Canon, NEF from Nikon, ARW from Sony, and others — you need the Microsoft Raw Image Extension, also available free in the Microsoft Store. Search for 'Raw Image Extension' and install it. This adds thumbnail and preview support for over 200 RAW formats. One honest caveat: some proprietary RAW formats from older or less common camera models are not covered even by this extension, and in those cases your only option is to convert the files to a universally supported format like TIFF or JPEG — which is something CocoConvert can handle directly in your browser without installing any desktop software.
When the Problem Is a Specific Drive or Network Location
Thumbnails that work on your C: drive but fail on an external hard drive, USB stick, or network-mapped drive are a different category of problem. For external drives, the most common cause is that Windows applies different performance settings to removable storage. Right-click the drive in File Explorer, select Properties, go to the Hardware tab, click Properties again, then the Policies tab. If you see an option for 'Better performance' versus 'Quick removal,' switching to 'Better performance' can help — though be aware this means you should always use 'Safely Remove Hardware' before unplugging the drive. For network drives (mapped drives or NAS folders), Windows often doesn't generate thumbnails at all by default because reading every file across a network to build previews is slow and expensive in bandwidth. There's no clean built-in fix for this; the standard workaround is to copy the files locally first, or to use a dedicated photo management application like FastStone Image Viewer or IrfanView, both of which generate their own thumbnail caches independent of Windows Explorer. Group Policy is another factor on domain-joined machines (common in offices and schools). An administrator can set the policy 'Turn off the display of thumbnails and only display icons' under User Configuration > Administrative Templates > Windows Components > File Explorer. If this policy is active, no amount of toggling settings will restore thumbnails — you'd need to ask your IT department to change it.
Convert Problem Files to Formats Windows Actually Supports
Sometimes the most practical solution isn't to fix Windows — it's to convert the files into a format that Windows handles without friction. If you have hundreds of HEIC photos from an iPhone, dozens of AVIF images downloaded from the web, or a batch of camera RAW files, and you don't want to install codecs or deal with registry edits, converting them to JPEG or PNG eliminates the thumbnail problem entirely and makes the files compatible with virtually every application on every platform. CocoConvert supports batch conversion of HEIC, AVIF, WebP, BMP, TIFF, and most common RAW formats to JPEG or PNG directly in the browser — no software installation required. Upload your files, choose your output format, and download the converted versions. For photos where file size matters, JPEG at 85% quality is a reasonable default that preserves visible detail while keeping sizes manageable. For images with transparency (like logos or UI screenshots), PNG is the better choice since JPEG doesn't support transparent backgrounds. One limitation worth being upfront about: CocoConvert has a file size limit per upload, and very large RAW files from high-megapixel cameras (some Sony A7R files exceed 80 MB) may hit that ceiling. For those cases, a local tool like Adobe DNG Converter or the free RawTherapee is a better option. The goal here is to match the right tool to the right problem, not to force every task through one service.
When Nothing Works: Advanced Troubleshooting Steps
If you've cleared the cache, verified folder view settings, installed the relevant codecs, and thumbnails still refuse to appear, there are a few more things worth checking before you consider a Windows repair. First, run the System File Checker. Open Command Prompt as Administrator and run sfc /scannow. This scans for corrupted Windows system files and repairs them automatically. The scan takes 10–20 minutes and requires a restart to complete repairs. Second, check whether your antivirus software is interfering. Some security suites — particularly older versions of Avast and certain enterprise endpoint tools — intercept file reads in a way that prevents thumbnail generation. Temporarily disabling real-time protection and then browsing the folder is a quick test; if thumbnails appear, add File Explorer (explorer.exe) to your antivirus exclusions. Third, if you're on Windows 11 and recently updated to version 22H2 or later, there was a known bug in certain builds where thumbnail generation for folders containing mixed file types would stall. Microsoft released a patch for this; check Windows Update and make sure you're fully current. Finally, if the problem appeared after a specific Windows update and nothing else has worked, the nuclear option is to use the Windows Recovery options to uninstall the most recent update: go to Settings > Windows Update > Update History > Uninstall Updates, and remove the most recently installed cumulative update. This is a last resort and should be reversed once a fixed update is available, but it's a legitimate troubleshooting step that Microsoft's own support documentation acknowledges.