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FAIL: Using Thumbcache Viewer to force a rebuild of specific thumbnails

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Kevin Routley edited this page Sep 12, 2021 · 1 revision

Update Sept 12,2021: the author points out the app does not actually remove the thumbnail(s) from the cache. The only way to force a rebuild is to:

  1. Make a copy of (not rename) any files to be rebuilt
  2. Nuke or rebuild the thumbnail cache.

Thumbcache Viewer is an application which allows you to view the contents of the Windows Explorer thumbnail cache. Here I will attempt to describe how to use the tool to remove specific file thumbnails from the cache, which will force Windows Explorer to rebuild those thumbnails. You probably do not want to have any Windows Explorer window open in icon mode for your target folder(s).

Note: while writing this I discovered the app does not handle network paths. You will likely need to map a drive letter for a network location!

  1. Run the app.
  2. Using the File\Open menu, find the thumbnail cache files. The app does not start you in the correct location, you must browse to the folder yourself. The files are located in:

C:\Users\<username>\AppData\Local\Microsoft\Windows\Explorer

aka

%localappdata%\Microsoft\Windows\Explorer.

<username> represents your system user name.

  1. Select all the "thumbcache_xx.db" files which are not 1KB in size. These are all the "active" thumbnail caches. Here is a screenshot of my cache folder, I will ignore the _1280, _1920, and _2560 files as they are empty.

  1. Having opened said cache files, the app shows a table that will look something like:

Note that the "Filename" column does not match anything on your system, it is internal to the cache!

  1. To find the actual file, use the "Tools\Map File Paths" menu. This is the initial view:

  1. Rather than scan your entire disk, I prefer to narrow the search as much as possible. For example, if I have a file I want to rebuild, I will find the folder in the dialog, and set up the file type appropriately. Here is a screenshot where I'm looking for files in "C:\Temp" and because I'm using DarkThumbs I'm looking for epub, cbr and cbz files:

  1. Click the "Scan" button, dismiss the popup, and click "Cancel".

  2. You can now scroll down the list in the main window [probably sort by Filename first] to find Filenames in the target folder. Here I show the files "mapped" into "C:\temp" as per step 6 above:

  1. Note there are multiple entries for different sized thumbnails. Select the file(s) you want to be rebuilt, and use the "Edit\Remove Selected" menu to remove them from the cache.

  2. Go back to Windows Explorer and see the thumbnails rebuilt.

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