mfc100u.dll: download the file and fix the error

32-bit and 64-bit Microsoft Visual C++ 2010 Scanned by antivirus

mfc100u.dll is a file of Microsoft Visual C++ 2010, the runtime library that a great many games and programs need to run. Its official description: “MFCDLL Shared Library - Retail Version”, by Microsoft Corporation.

If it is missing or damaged, Windows displays for example: “The program can't start because mfc100u.dll is missing from your computer.” Two methods can fix the error, below.

Method 1 · quick · about 1 minute

Download only mfc100u.dll

Ideal if only this file is reported missing: you replace a single file, without reinstalling anything.

⇓ Download the 64-bit version ⇓ Download the 32-bit version .zip file: the DLL + its instructions · downloaded 47,332 times

Which version should you choose? The one that matches the program showing the error, not Windows: a 32-bit game or program needs the 32-bit DLL, even on 64-bit Windows. If in doubt, try the 64-bit version first, then the 32-bit one if the error persists or becomes “0xc000007b”.

Version: 10.00.40219.01 (64-bit)10.00.40219.325 (32-bit)
Size: 5.6 MB (64-bit)4.42 MB (32-bit)
Architecture: 64-bit (x64)32-bit (x86)
Publisher: Microsoft Corporation

Then:

Extract mfc100u.dll from the zip file and copy it to the folder of the program showing the error (where its .exe file is).
Still getting the error? Copy it to C:\Windows\System32 (64-bit DLL) or C:\Windows\SysWOW64 (32-bit DLL on 64-bit Windows), then restart.

SHA-256 (64-bit): 39955dbbe00391955fa8313ff1b9c815be7b6aa615d36345e579476e789e91ec · Check on VirusTotal
SHA-256 (32-bit): bc50848aeef466dff4a3d8c386bf0d0ec35b8e5b438031ae885aa5371f2e1a42 · Check on VirusTotal · Product: Microsoft® Visual Studio® 10

Method 2 · complete · official method · 5 to 10 minutes

Reinstall Microsoft Visual C++ 2010

Microsoft still offers the Microsoft Visual C++ 2010 package (an older version, still required by many games). It restores mfc100u.dll and the files of the same family.

Official Microsoft page of the Visual C++ packages

On the Microsoft page, download the Visual C++ 2010 package in its x86 version, and also x64 if your Windows is 64-bit.
Run them, then restart your computer. Already installed? Settings › Apps › the 2010 package › Modify › Repair.

Complete guide: Visual C++ errors (msvcp, msvcr, vcruntime)

Error messages related to mfc100u.dll

The program can't start because mfc100u.dll is missing.
Error loading mfc100u.dll. The specified module could not be found.
Failed to load mfc100u.dll

Why does this error occur?

Microsoft Visual C++ 2010 is not installed: new computer, reinstalled Windows, or a program that does not install its own prerequisites.
The file was deleted or damaged: another program was uninstalled, an overly aggressive cleanup, an antivirus.
Wrong architecture: a 32-bit program cannot use the 64-bit version of the DLL, and vice versa.

Files of the same family (Microsoft Visual C++ 2010)

mfc100.dll msvcp100.dll msvcr100.dll vcomp100.dll

Frequently asked questions

Is mfc100u.dll a virus?

No: it is a legitimate Microsoft file. Only be wary of a copy found outside C:\Windows or a program’s folder; you can compare its SHA-256 fingerprint with the one shown on this page.

Should I install the 32-bit or the 64-bit version?

On 64-bit Windows, install both: a 32-bit game needs the x86 version, even on 64-bit Windows. On 32-bit Windows, only the x86 version can be installed.