How to fix CCleaner crashes

Radu Tyrsina
by Radu Tyrsina
Founder & Editor-in-Chief
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  • If you have been a Windows user for a long time now, then CCleaner is no stranger to you.
  • The problem also arises after you have modified or updated CCleaner, which can corrupt the Windows registry if the change is incomplete.

If you have been a Windows user for a long time now, then CCleaner is no stranger to you. For starters, CCleaner works to scan and delete unnecessary files to free up space in your computer storage. These temporary files emerge from programs, report logs, and Internet Explorer files as you open them. However, the disk cleanup software is unable to remove cache files from other browsers, including Chrome and Firefox.

The tool also clears your browsing history and your most recently opened files. This is especially helpful for users who want to maintain a certain level of privacy. As a third-party software, CCleaner also helps to resolve computer issues arising from old or corrupted files. While the software is designed to help fix computer problems, it can sometimes run into an error itself. Users are reporting a crash problem in CCleaner while the tool is running.

Several factors can cause CCleaner to crash (C000021A error), including a corrupt download or improper installation of the software. The problem also arises after you have modified or updated CCleaner, which can corrupt the Windows registry if the change is incomplete. Malware infection is another major contributor to CCleaner crash as it corrupts Windows system files or CCleaner files. However, even non-malware programs can cause CCleaner to crash as well, when files related to the disk cleanup tool are inadvertently deleted upon running those programs. Below is a list of solutions to help you fix CCleaner crashes.

Solution 1 – Perform manual repair of Windows registry

  1. Before beginning the manual repair of Windows registry, backup the registry files related to C000021A error.
  2. Then type command in the search box found in the Start button (if you are using Windows 7) or beside the Start button (for Windows 10 or Windows 8 users).
  3. Hold CTRL-Shift on the keyboard before hitting Enter. Select Yes once a permission dialog box appears.
  4. Type regedit in a black box that will appear with a blinking cursor and press Enter.
  5. Then choose CCleaner in the Registry Editor to backup the program before clicking Export in the File menu.
  6. Select a folder in the Save In list where you want to save the CCleaner backup key.
  7. Click Selected branch in the Export Range box before hitting Save. The backup is now saved as a .reg file.

The manual process of editing the Windows registry, however, is recommended only for advanced computer users. Even the slightest mistake in the use of Registry Editor can cause irreversible problems to your operating system.

Solution 2 – Remove temporary files and folders

Prolonged Internet surfing and computer use pile up a huge mass of junk files. Users sometimes forget to clean up these useless files, which leads to slow CCleaner response. This eventually results in a C000021A error as files begin to run into conflict or the hard drive accumulates excessive loads of files. A disk cleanup operation will help to resolve the problem. While the Windows Disk Cleanup tool is the default software installed in most Windows computers, there are other programs meant to help optimize your machine.

To initiate the Windows Disk Cleanup process, follow these steps:

  1. Type command in the Start button’s search box.
  2. Hold CTRL-Shift before hitting Enter and a permission dialog box will crop up. Select Yes.
  3. In a black box with a blinking cursor, type cleanmgr and press Enter.
  4. The Windows Disk Cleanup tool will now calculate how much space you can free up and allow you to choose which category you want to clean out.

Solution 3 – Scan your computer for malware

The C000021A error sometimes arises due to the presence of malware in your computer. A malicious software could corrupt and remove runtime-related files. Many anti-malware programs could help resolve this issue. If you still do not have an anti-virus software, head on to our list of the best anti-virus programs for Windows.

Read also: 10 best antivirus programs for browsing

Solution 4 – Perform Windows System Restore

Recent changes you make to your computer can sometimes lead to unexpected program errors. If you’ve previously installed a new software in your PC or modified an existing application, chances are that these changes might have caused your CCleaner to crash. You can restore your Windows system to a previous setting when it was performing fine with the Windows System Restore tool. This process restores your computer’s system files and programs to resume normal PC operation, thus possibly fixing the C000021A error.

  1. Type system restore in the Start button’s search box and press Enter.
  2. Select System Restore in the results and key in your administrator password if required.
  3. Follow the recommended steps to select a restore point, a certain period when your machine was working okay.

Solution 5 – Update device drivers to fix the C000021A error

There’s a good chance that outdated PC device drivers are causing the C000021A error. This is not entirely a cause for so much worry, however. Driver updates are always available to download from software manufacturers. The challenge, though, is the arduous task of finding the exact driver for C000021A-related device. Worse, installing the wrong driver update can even lead to further issues. Thanks to driver update tools available in the market, you can avoid the difficulty associated with updating device drivers. Follow our recommended steps for updating old drivers in Windows 10.

Solution 6 – Download and install Windows updates

Microsoft constantly rolls out updates to improve Windows. But most users frequently ignore these updates, inadvertently or otherwise. These updates, in fact, usually help to fix C000021A errors with the newest Service Pack and the latest patches. To see the latest Windows updates, simply open the Windows Update dialog box and click Install Updates.

Solution 7 – Reinstall CCleaner

If all else fails, you can simply uninstall the CCleaner program and reinstall the tool from Piriform. This process does not take much effort. Go to Programs and Features in the Control Panel and find CCleaner. Uninstall the program by following on-screen directions. Once this is done, visit Piriform’s website and download the latest version of CCleaner.

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