If malware has taken root on your system, it may try and prevent AVG Anti Virus from updating itself in order to remain undetected.
I have tried to uninstall AVG Tuneup but it refuses to uninstall.
I think this company has become completely corrupt and I'm demanding a refund. I have found that I can fix this for a while by running System Mechanic. I rate AVG Internet Security by itself, 4 out of 5, but the persistent problems with being constantly harassed to upgrade PC Tune Up unfortunately bring my total satisfaction rating down to 2.
Once any identified malware threats are spotted and removed, try the AVG Anti Virus update again.
The problem may be caused by an issue with the AVG Anti Virus program itself rather than anything external.
Because of this risk, we highly recommend using a trusted registry cleaner such as Win Thruster (Developed by Microsoft Gold Certified Partner) to scan and repair any Error 0x E001D026-related registry problems.
Using a registry cleaner automates the process of finding invalid registry entries, missing file references (like the one causing your 0x E001D026 error), and broken links within the registry.
If you've previously canceled an update partway through, for example, it can interfere with future updates.
Uninstall AVG Anti Virus completely from your system using the "Uninstall a program" link in Control Panel, then reinstall the software using the latest version from the AVG website.
These troubleshooting steps get progressively more difficult and time consuming, so we strongly recommend attempting them in ascending order to avoid unnecessary time and effort.