Norton antivirus is the robust software which protects your device from emerging threat created by hackers. It secures your valuable data from malware, viruses, Trojans, rootkits and ransomware attack. It is very easy to install but some users encounter Norton Error Code 8506 and 421. In this blog, you will read the solution of Norton Error Code 8506 and 421.

Symptoms of Norton Error Code 8506 and 421:

The symptoms of Norton Error Code 8506 and 421 are when active program window crashes, other software programs might have crashes your system with error 421, windows speed is reduced and works slowly, and computer hangs frequently.

Causes of Norton antivirus Error Code 8506 and 421:

The causes of the Norton Error Code 8506 and 421 are incomplete or corrupt installation of Norton antivirus, corrupted windows registry entries, virus or malware attack affected Windows system files, and other software program mistakenly deleted Norton antivirus related file.

Read Also – How to Get Rid Of Norton Error Code 3035 6?

Solution To Fix Norton Error Code 8506 and 421:

1: Repair the Registry Entries:

  • Go to the Start menu and then type “command prompt” in the search bar.
  • In the search result, when you find ‘Command Prompt’ option, just right-click on it.
  • Now, select the ‘Run as administrator’ option from the list.
  • After this, type “regedit” in the command line and then press Enter key.
  •  Now, you have to select the portion which you want to back up from the ‘Registry Editor’ window.
  • Then go to the File tab and select the ‘Export option from the list.
  • From the ‘Save in’ option, you have to select the folder where you want to save the backup file of the Norton antivirus.
  • Just change the name of the file to ‘Norton 360 backup’.
  • After this, click on the ‘Selected Branch’ option from the ‘Export Range’ pop-up box.
  • Hit on the Save button to save the ‘.reg’ file extension.
  • Here the backup of the registry file is successfully created.


Now, edit the registries to repair them.

  • For this, locate the key which you want to edit.
  • Now, press the F and Ctrl key altogether to open the Find dialog box.
  • Here, just type the name of the key and click on the ‘Find Next’ button.
  • You should click twice on the key which you want in the list.
  • Now, edit the value data of the key.
  • At last, hit on the OK option to apply the changes and then restart your device.

2: Remove the Junk files:

  • Go to the Start menu and then visit to the ‘Computer’ section.
  • Now, right-click on the main hard drives i.e. C: drive.
  • Just select the ‘Properties’ option from the list.
  • After this, click on the ‘Disk Cleanup’ option.
  • In the next Window, there is the list of some items.
  • Just select all the items and then right-click on them.
  • Here, select ‘Remove’ option from the list.
  • In case, you want to clear more junk files, just hit on the ‘Clear up system files’ option.
  • Then, select the categories which you want to delete and click OK button.
  •  Now, click on the ‘Delete Files’ option to finish the process.

3: Update the Video Graphics Driver:

  • Go to the Start menu and then type “device manager” in the search bar, press Enter key.
  • Now, click on the ‘Display adapters’ option to expand it.
  • After this, just right-click on the ‘HD graphics card’ and select the ‘Properties’ option from the list.
  • Here just go to the Drivers tab just to check for the available updates.
  • If there are latest updates available, just install it.
  • When you update it, just restart the system.

4: Reinstall the Norton Antivirus:

  • Go to the website of Norton and then download the ‘Norton Remove and Reinstall’ tool.
  • After this, just save the file on the Windows desktop or sometime the file is stored automatically to its default location.
  • Now, press J and Ctrl key altogether to open the Download window of the browser.
  • Then, click twice on the NRnR icon.
  • Carefully read the license agreement and hit on Agree button.
  • Now, click on the ‘Remove & Reinstall’ option.
  • After this, confirm it by clicking on the Continue button.
  • At last, click on ‘Restart Now’ option to apply the changes.

These methods help you to solve the Norton Error Code 8506 and 421. If you are still facing any problem, then visit to the site of Norton Antivirus.