Some older versions of CCleaner are not compatible with Windows 10 because of the folders they clean.
CCleaner v5.45 and below clean a folder that Microsoft used to store old Windows install files (called the .old folder). However, Windows now uses this folder to store files it needs, so cleaning this folder could cause issues.
To avoid any potential problems, if a Windows 10 user tries to run an incompatible version of CCleaner, Microsoft will display a notification asking them to update.
If you’re using an older version of CCleaner and you see this notification, please update to the latest version. Alternatively, you can update here.
We always recommend that CCleaner users keep their software up to date. Here’s why.