Clean the Windows Registry

This page explains what the Windows Registry is, why CCleaner cleans it, and how to clean it. To skip to instructions for Registry > Registry Cleaner, go to Clean your Registry with CCleaner for Windows further down this page.  

How the Windows Registry affects you:

The Windows Registry is a set of files that contains settings for your Windows PC, such as what program to use to open HTML files, when your antivirus program should run, or what desktop background you use. You can read more about the Windows Registry on Wikipedia.

Why CCleaner cleans the Windows Registry:

Over time, the Registry can become cluttered with missing or broken items when installing, upgrading, and uninstalling software or updates. CCleaner cleans out the Registry to help prevent errors from occurring, which can help it run faster.

Clean your Registry with CCleaner for Windows:

  1. In CCleaner, click the Registry icon at left to view the Registry Cleaner menu.
  2. You can then select the items under Registry Clean you want CCleaner to scan (they are all checked by default). This is for advanced users. We recommend you leave all the items selected.
  3. Click Scan for Issues. You'll see a progress bar and a list of potential issues.
  4. You can review the list of issues once the scan finishes (this is really for advanced users). To save the list to a text file, right-click anywhere inside the list, and then click Save to text file.
  5. If you want CCleaner to skip any of the issues it's found (permanently), right-click the issue, and then click Add to Exclude List. You can review the current set of excluded files, folders, and Registry entries in the Exclude section of Options > Exclude in CCleaner.
  6. Click Fix Selected Issues to fix the Registry problems.
  7. CCleaner prompts you to back up the Registry first. We strongly recommend you click Yes.
  8. Choose a location on your computer to save the Registry backup. The file name ends in .REG. Click Save.
  9. CCleaner displays the first Registry problem on the list (like Unused File Extension .oxps) and a proposed solution in the same modal window, giving you the option to Fix Issue, etc.

Note: Please see the screenshot below to see what 9. is referring to.

CCleaner Professional, Registry, Registry Cleaner window dialog box showing an example of an issue found by CCleaner's Registry Cleaner.

This dialog box shows an example of an issue found by CCleaner's Registry Cleaner.  

10. Do one of the following (see screenshot for reference):

  • To fix all issues at once, click Fix All Selected Issues. Click OK. Click Close when CCleaner the problems.
  • Review the issue and proposed solution. To fix this specific issue, click Fix Issue. CCleaner then goes to the next issue. To skip this issue and go to the next one, click the >> button. Repeat this process for all of the problems that CCleaner manages to find. We recommend this choice for most users (for safety).
  • To stop making changes to the Registry, click Close. If you do this by mistake, click Fix Selected Issues again.

We recommend examining Registry Cleaner's fixing options carefully:

This is important if you select parts of the Registry that you want to clean (see screenshot) but are unsure what will happen if you remove them. We've made CCleaner's fixing options (listed beneath Registry Cleaner) in Registry > Registry Cleaner to help reduce potentially harmful results. It’s always safer to leave an entry than to remove it if you’re not 100% sure.


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