AVG Antivirus Free Update Program Version Button Greyed Out

Hello

I'm using AVG Antivirus Free on win 7 32 bit. Last night I recognize this error from AVG icon on taskbar  that saying "You Are Unprotected". But when I open the AVG Interface it says "You Have Basic Protection"

After I check I found that in update menu the Update Button for program version become greyed out, while in virus definition it work just fine.

I will include the pic later


Just want to ask why my program version Update Button become greyed out ? What causing this to happen ?

Thank you for the info & explanation, Erick. 

During the update of 18.6 to 18.7, some files may get corrupted or missed which causes this issue. It will get fixed once we uninstall and reinstall your AVG Antivirus free version. 

Refer the below article to run AVG clear and remover tool which remove the traces of AVG: 
http://support.avg.com/SupportArticleView?urlname=How-to-troubleshoot-issues-after-upgrade-to-the-latest-AVG-antivirus-product

Reinstall AVG Antivirus free as suggested here: http://support.avg.com/SupportArticleView?urlname=Download-and-install-AVG-AntiVirus-Free