Using the sources provided, you can fix the AVG Antivirus Update Error by taking these steps:
Update Windows: While some of your antivirus software update errors could be a result of your provider’s shortcomings, the problem could also be from you as that error usually requires an up-to-date Windows.
Use a Troubleshooting Tool: When the probable root for your error is no longer insufficient storage, installing a troubleshooting tool that functions to keep your Windows organized and error-free could be of help. Use the steps given to run the tool and combine it to fix this error.
Repair AVG Antivirus: When you encounter this error, you will have to repair AVG Internet Security as administered by the link provided. Once you have repaired it, restart the pc and check to see if the problem persists.
If it does, reach out to AVG Support for further instructions. Hence, the solution to this problem is by updating Windows, using a troubleshooting tool, and by repairing AVG Internet Security.