[Fixed] Norton Error 8506 and 421

While opening Norton antivirus software, you might often encounter Norton error 8506 and 42. One can also face this issue while trying to install the software while Norton Internet Security is already active. Moreover, it can also occur if you try to do the same while shutting down or starting your Windows system. 

On confronting this error, the PC might crash many times or even get freeze very frequently. It might also create a sluggish response for both the keyboard and mouse respectively. 

What are the causes behind Norton 360 error 8506 and 421 on windows 7?

Norton error 8506 and 421 can occur due to incomplete installation or any inappropriate download of the Norton Internet Security Application. However, despite that, there are other causes that might generate such an error. Here we have mentioned some of them below:

  • Any registry corruption while installation/uninstallation
  • Malware or Virus attacks
  • Falsely or maliciously deleted Norton Internet Security files
  • Corrupted files within the system

How to Resolve Norton internet security error 8506 and 421?

Although the problem is pretty common among users. This entire scenario is frustrating and thus needs an immediate fix. For precise knowledge, here we have mentioned some of the solutions for you in brief.

Solution 1: Clean System Junk Files

At first, we will use the Disk Cleanup Tool to clean system junk files as its accumulation can result in such error on your system. To do so, follow the steps given below orderly:

  • Go to Start and then within the search bar type “disk cleanup”.
  • Choose the Disk Cleanup from the list and then the drive which you want to clean. Press Ok.
  • Head over to Files to delete and select the type of files you want to remove. Then, click on Ok.
  • If you want to free some extra space then, select cleanup system files from the Disk Cleanup.
  • Choose the files you want to remove and then press Ok.

Solution 2: Remove and Install the Norton Antivirus Again

As the problem is correlated with the antivirus software, it is recommended to install the Norton Antivirus again and check whether it resolves the error for you. To do so, perform the following steps.

  • Go to Start and then Control Panel.
  • Within the Programs section, check the list of installed programs and click the “Uninstall a Program”. Now, select the Norton product from the list.
  • Click on the Uninstall button. After that, click on “I plan to reinstall a Norton product. Please leave my settings behind” link (if you want so).
  • Again, click on Next to start the uninstallation of Norton and then click on Restart Now option.
  • Insert the Norton Security Software CD and wait for the installation wizard to start. However, if it does not start itself, you need to go to “My Computer” and then click twice on the CD-Drive. Click on “Setup.exe” and follow the instructions appearing on your screen to install Norton successfully. 

Solution 3: Update Your Device Drivers

An outdated device driver can also be responsible for this error and thus it is important to fix it by following the steps given below sequentially.

  • Navigate to Control Panel and then select Device Manager.
  • Choose and expand the driver category which you want to update.
  • Right-click on the hardware icon and select the Update Driver or Update Driver Software option.
  • Again, click on “ Search automatically for updated driver software” option.
  • On doing so, the device manager will download and install any new update (if available) for you. 

Solution 4: Start a Malware Scan

As mentioned earlier, you are very likely to face this error if your system is affected by any virus or malware attack. Thus, for such cases, it is recommended to start a malware scan.

Windows has an inbuilt anti-malware software (Windows Defender) that helps people get rid of any virus or malware within their system. Here is how you can use it to start a malware scan on your system.

  • Go to Settings and select Update & Security. Locate and click on Windows Defender.
  • Once the Windows Defender box displays, click on Windows Defender Security Center.
  • Again, click on the Virus and Threat Protection button and then on Quick Scan.
  • If you want a full, custom, or offline scan, click on Advanced Scan within the Windows Defender Security Center window. 

Solution 5: Use Windows System Restore

System restore is useful in restoring the system to a point where it worked absolutely fine. Thus, doing so might restore the system to the time where the error did not exist. Here we will be using Windows System Restore through Command Prompt. Hence, follow the steps given below to do 


  • On starting the computer, press the F8 key multiple times so that the Windows Advanced Options menu can appear. 
  • Choose “Safe Mode with Command Prompt” and press the Enter button.
  • Type the following command and make sure to press Enter after each line
  • CD restore
  • rstrui.exe 
  • Now, click on Next.
  • Choose any available restore points and then Press on Next to restore the system to an earlier condition.

Solution 6: Update Windows to Latest Version

If none of the solutions mentioned above work for you then it is recommended to update the Windows to the latest version by following the steps given below.

  • Go to Settings>Update & Security>Windows Update
  • Click on Check for Updates.
  • Again, go to the “Feature Update to Windows 10” and click on the “Download and install button”.
  • Lastly, click on Restart Now after downloading the update. 

So these were some of the solutions following which you should be able to fix the Norton internet security error 8506 and 421 successfully.