This depends on your version of CCleaner, your Windows Store settings, or which antivirus program you use. These are the three main reasons why Windows 10 might block your attempt to install CCleaner. We go into these in more detail below.
Do you use CCleaner version 5.45 or below?
If yes, these older versions of CCleaner for Windows are not compatible with the most recent versions of Windows 10. We recommend you download the latest version of our app to fix this issue:
Does your version of Windows 10 only allow apps from the Microsoft Store?
If either one of the messages below appears when you try to install CCleaner, this means you need to change your Windows settings so you can buy or download software for free from elsewhere:
1. The app you're trying to install isn't a verified app from the Store
2. You can only install apps from Microsoft Store
How to change this Windows setting:
Go to Settings > Apps > Apps & Features in Windows. Change your setting for the Installing Apps from Allow apps from the Store only to one of these two options below. The second of the two means that Windows doesn't ask for your permission when you choose to download software:
1. Warn me before installing apps from outside the Store
2. Allow apps from anywhere
Note: View the screenshot below if you're not sure how these options appear in Windows.
Choosing the setting Warn me before installing apps from outside the Store means you still get this message from Windows:
The app you're trying to install isn't a verified app from the Store
When it appears, click Install Anyway to continue.
Note: If you're unsure what this message looks like, see the screenshot below.
Note: System behavior of this sort sometimes occurs if you use Windows 10 in S Mode. You can't install CCleaner in S Mode.
Does your antivirus software flag CCleaner as "risky" software?
Some antivirus apps flag new CCleaner releases as risky. This is because the analysts working on these apps haven't necessarily had the chance to look at them in detail. Software companies usually correct this type of problem within 12-72 hours, depending on which antivirus app you have and the brand.
Note: Every new version of CCleaner for Windows goes through cybersecurity testing before release, and the "slim" build version of our app can sometimes stop these errors with antivirus software.