A bug in the Windows 10 registry editor (Regedit.exe) makes it crash since the large Fall update. The bug causes it to end up in an endless loop after which the application crashes. The issue happens when the search reaches a key of which the full path is longer than 255 characters.
(Image credit: Heise)
The German website Heise found that once Regedit attempts to access a subkey with a full path longer than 255 characters, the application gets stuck in an infinite loop. Regedit also fully utilizes the CPU when in the loop. Trying to end the search by clicking 'Cancel' finally crashes Regedit after which the application restarts. The Windows Event Viewer lists an error with commctl32.dll. Heise so far only found that the issue occurs on long keys, Regedit always shows the issue when the first key longer than 255 characters is found.
Also previous versions of Windows 10 had issues with Regedit and long keys. In build 10240 (RTM) nothing happened when a long key was double clicked. In build 10586, the version before the Fall Update, an error message occured when such a key was double clicked.
Heise also mentions that it's unclear how these long keys end up in the registry. They found that a clean installation of Windows 10 with the Fall Update didn't have any long keys but nevertheless most computers they tested did contain them after some time. These kind of keys should have never end up the registry because it has a limit of 255 characters. Developers should know to not use longer key as they also caused issues in the past.
