Many users install Malwarebytes because it's one of the best freely available anti-malware utilities. However, some users can't install it because of a Runtime Error issue. Those users see an error message that says "Runtime Error (code): Could not call proc" when trying to install Malwarebytes.

If you're running into this issue, you might miss out on free and excellent protection for your PC. So, how can you ensure your computer is safe while you're online? By fixing the Runtime Error! Here's how.

1. Run the Program Install and Uninstall Troubleshooter

Microsoft's Program Install and Uninstall troubleshooter might be useful for fixing the Runtime Error since that's a software installation issue. This troubleshooter is designed to resolve problems that block users from installing or removing software.

You can download and run the Program Install and Uninstall troubleshooter like this:

  1. Open Microsoft's download page for the Program Install and Uninstall troubleshooter.
  2. Select Download troubleshooter on that webpage.
  3. To open that troubleshooter, press the Windows + E and bring up whatever folder contains its downloaded file. Then double-click the troubleshooter's MicrosoftProgram_Install_and_Uninstall.meta.diagcab file.
  4. Click Next to view two alternative troubleshooting options.
  5. Select Installing to bring up a program list within the troubleshooter.
    The Installing option
  6. Then select Malwarebytes if it's in the program list. If it isn't there, click the Not listed option.
    The troubleshooter's program list
  7. Click Next to start the troubleshooting.

2. Delete Malwarebytes' Certificates

Runtime Error often occurs because of untrusted Malwarebytes certificates on users' PCs. Many users have been able to resolve this issue by erasing untrusted certificates for Malwarebytes. This is how you can delete those certificates in Windows 11/10:

  1. Press Windows + R to open the Run Dialog Box.
  2. Enter certmgr.msc inside Run's command text box.
  3. Click OK to access the Certificate Manager tool.
  4. Select Untrusted Certificates on the left of the certmgr window.
    The certmgr window
  5. Click Certificates in the window's Object Type area.
  6. Look for Malwarebytes' certificates in the Untrusted Certificates folder.
  7. Right-click an untrusted Malwarebytes certificate and select Delete.
  8. Click Yes to confirm the certificate's deletion.
  9. Repeat the previous three steps to delete all the untrusted certificates associated with Malwarebytes you can find.
  10. Exit the Certificate Manager tool.
  11. Reboot your PC by clicking Restart on the Start menu.
  12. Try installing the Malwarebytes software.

3. Change the Temp Folder's Location

Another issue that could cause the Runtime Error is when the Windows %TEMP% folder is not in its expected location. In this case, restoring that folder to its default location could solve the Runtime Error problem. To do so, set the %TEMP% folder's placement with some CMD commands as follows:

  1. Open the Command Prompt as an Administrator.
  2. Input this set Temp command and hit Enter: 
            set TEMP=C:\Windows\temp
    The set TEMP command
  3. Then execute this command: 
            set TMP=C:\Windows\tmp
    The set TMP command
  4. Finally, input the following command text and press Return: 
            cd "%USERPROFILE%\Downloads"
    The cd %USERPROFILE% command
  5. Exit the Command Prompt app.
  6. Open the Malwarebytes download page for the latest version of that software.
  7. Then select the Free Download for Home option.
  8. Click the downloaded MBSetup.exe file with your mouse's right button and select Run as administrator to see if you can install Malwarebytes.

4. Troubleshoot the Error With the Malwarebytes Support Tool

The Malwarebytes Support Tool is a troubleshooting utility specifically designed for fixing Malwarebytes issues. That utility's Clean option can resolve the Runtime Error by eradicating all remnant Malwarebytes files it finds. You can also elect to reinstall the anti-malware software with that utility.

This is how you can troubleshoot the Runtime Error with that support tool:

  1. Open the Malwarebytes Support Tool download page.
  2. Scroll down to How do I use the Malwarebytes Support Tool? and click the link on Download the latest version of the Malwarebytes Support Tool.
  3. Open the File Explorer (the library folder icon on the taskbar) and open whatever directory contains the Malwarebytes Support Tool installer.
  4. Open the file you just downloaded to bring up the Malwarebytes Support Tool setup wizard.
  5. Select Accept the License Agreement checkbox, and click Next to install.
    The Accept License Agreement checkbox
  6. Click the tool's Advanced tab.
  7. Press the Clean button.
    The Clean option
  8. Select Yes on the Malwarebytes Cleanup dialog box.
  9. Click OK to reboot the PC after the cleanup process.
  10. After restarting Windows, select Yes on the Reinstall Malwarebytes for the Windows prompt that usually automatically opens. Or download and open the setup wizard for Malwarebytes to install the software if you don't see that dialog box.

5. Run Deployment and Image Servicing and System File Checker Scans

System file corruption is another potential cause for this Malwarebytes installation error. To remedy that, your best bet is to run a System File Checker scan. It's also advisable to run a Deployment and Image Servicing scan to resolve Windows image issues. These are the steps for running both scans:

  1. Open the Command Prompt.
  2. Run the Deployment and Image Servicing scan by executing this command: 
            DISM.exe /Online /Cleanup-image /Restorehealth
  3. To run the System File Checker, enter this text and press Return: 
            sfc /scannow
    The SFC scannow command
  4. Wait for the SFC tool to finish the scan and show an outcome message.

Once you complete the scan, try installing Malwarebytes again to see if the issue is resolved.

6. Run the CHKDSK Tool

If you're still trying to resolve Runtime Error after applying resolutions one to five, run a CHKDSK scan to check the condition of your PC's hard drive. There could be an HDD or SSD error causing the installation issue on your PC. The CHKDSK (Check Disk) tool can repair any file system errors detected.

You can run a CHKDSK scan inside the Command Prompt like this:

  1. Launch Command Prompt as an administrator.
  2. Then type in and execute this Check Disk scan command: 
            chkdsk C: /f /r
  3. Press the Y button on your keyboard to schedule the Check Disk for a system restart.
    The chkdsk command
  4. Exit Command Prompt, and select Windows' Restart option.
  5. Wait for the Check Disk scan to do its stuff after restarting.

Install Malwarebytes in Windows 11/10

The confirmed Runtime Error solutions in this guide will likely resolve that error so you can install and use Malwarebytes. However, we cannot promise they'll fix this installation issue for everybody. If you need further troubleshooting guidance for Runtime Error, you can submit a support request on the Malwarebytes website.