1.When a DLL error occurs, restart your PC and then try to start the application that generated the error. Quite often, DLL errors, such as the mfc71.dll error, occur due to a temporary situation which is resolved when you reboot the PC.
2.If the error still occurs, check your Recycle Bin to see if the file that is generating the errors has not been deleted by mistake. If you find the file there, restore it to resolve the issue. If you have emptied your Recycle Bin, you may need to use a file recovery software to get your file back.
3.A DLL error, such as the missing Mfc80u.dll error may occur if your computer is infected by some type of virus. If you fear this, it is best that you use a good antivirus tool to perform a thorough scan of your computer and weed out all malicious data from it.
4.Next, update your Windows operating system, applications and device drivers. To update your Windows, you may either use the Windows Update option in the Start menu or simply enable the Automatic Update feature in the Control Panel. For third-party applications, check to see if they come with an update option. If the option is there, you can use it to update your applications. Otherwise, it is best that you visit the application manufacturer Web site and then download and install the latest updates. Updating device drivers is often a complex and tedious procedure, which is quite prone to errors. So it is best that you use a reliable driver scanner tool that will automatically keep a track of all drivers on your computer and update them with most compatible and suitable driver updates.
5.All DLL files need to register themselves in the Windows registry to be able to function on your computer. If there is an issue with one or more DLL registry entries, DLL errors may occur. Many malware programs also modify existing registry entries to generate errors. To resolve such issues, you need to scan your registry for incorrect and invalid information and fix it. Although you can do some amount of registry fixes by using the Windows Registry Editor (regedit) tool, the task is quite complex and the chances of mistakes are quite high. This is the reason why, several PC experts recommend and even use, a reliable registry tool to scan, clean, and fix the registry.