TortoiseSVN icons overlay not showing after updating to Windows 10

Had same issue, and was solved by running regedit, erasing some entries in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\explorer\ShellIconOverlayIdentifiers and restarting. Deleting OneDrive1... enties was not permited, but I had some from Google Drive. You can also make a bakup by double-clicking in the registry directory and doing an "Export" to a file.

On Windows 10, most of the entries are used by OneDrive and you won't have permission to remove them. In order to do so, right click on the entry (Example: "OneDrive1", then click "Advanced", then click the link labled "Change" at the very top next to "Owner". This lets you change the owner. Type in your username and hit OK. Now give yourself "Full Control" and then apply it. Now you should be able to delete or rename it.

I fixed my problems with TortoiseSVN icons not showing up in Windows 10, for the special case where my repository was on a removable drive.

There is a Tortoise setting that determines which Drive Types the icons are used with: Drives A: and B:, Removable drives, Network drives, Fixed drives, CD-ROM, RAM drives, and Unknown drives.

It was NOT a problem with the naming of the icon overlays in the Windows Registry.

The names were automatically prefixed with "1", "2", etc.

to force them (in my computer) alphabetically at the top of the list just before the OneDrive icons.

So, all of the icons were within the top 15. To get to the Tortoise settings, right click on Desktop or a folder and then choose TortoiseSVN > Settings.

In Settings, choose Icon Overlays. There'll you find the Drive Types settings.

As in current recommended answer mentioned, you need to sort the entries of the overlay identifiers in the registry. I haven't deleted those OneDrive or GoogleDrive entries but renamed all Tortoise Folders by adding 3 spaces to bring them on top. Just restart and even with Tortoise SVN client 1.7.9 you'll see your SVN overlay icons under Windows 10 again.