I was looking for free anti-virus protection for my laptop. Since it’s not a powerful machine I wanted something lightweight, just to protect me from those adware and browser hijacker viruses. So, I came across AVG Anti-virus. After the installation of AVG when I tried to launch it the system error avgui.exe appeared saying that the program can’t start because mfc100u.dll is missing from your computer. Try reinstalling the program to fix this problem. Re-installation of the AVG didn’t solve the mfc100u.dll is missing problem so I tried another solution that always works for missing dll files.
It’s not the first time that I am having dll is missing error and usually I was able to fix them by reinstalling DirectX or the program. However if that doesn’t work there is another trick that I am always using – simply copying the genuine dll file into the program folder. To fix the mfc100u.dll is missing error in AVG you just need to download and install genuine mfc100u.dll from here: http://fix4dll.com/mfc100u_dll.
This should fix your mfc100u.dll is missing error in AVG or in any other application. I found that a lot of users having mfc100u.dll is missing in Witcher 2, Farcry 3. Now, you know the trick, simply download and install that file and it will fix your issue.