mfc100.dll Not Found on Windows: Causes, Fixes, and Safe Repair

The mfc100.dll error usually appears when an older Windows program cannot find the Microsoft Visual C++ runtime it needs. mfc100.dll belongs to the Visual C++ 2010 runtime family, so the safest first fix is installing or repairing the matching Microsoft Visual C++ 2010 redistributable.

Before changing anything, note:

• Which program or game shows the error.
• Whether it started after an update, reinstall, antivirus scan, or cleanup.
• Whether the application is 32-bit or 64-bit.
• Whether Windows is 32-bit or 64-bit.
• The complete wording and any path shown in the message.
• Whether mfc100.dll is missing, quarantined, or present beside the application.

What is mfc100.dll?

mfc100.dll is a Microsoft Foundation Class runtime library from Visual C++ 2010, also called Visual C++ 10.0. Microsoft’s Visual C++ file inventories list the file in both the x86 and x64 Visual C++ 2010 redistributable packages.

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It is part of a shared runtime used by applications compiled with Microsoft Visual C++. Related runtime files can include:

• mfc100u.dll
• mfcm100.dll
• msvcp100.dll
• msvcr100.dll
• atl100.dll
• vcomp100.dll

The exact description or internal-name field for this file is not established by the Microsoft pages covering the package. Do not rely on a supposed universal description, version, or file size.

mfc100.dll is not normally an original core Windows DLL. It may be installed by:

• the Microsoft Visual C++ 2010 redistributable;
• the application’s own installer;
• an application-local deployment beside the program executable.

Centrally installed Visual C++ files are normally placed in %windir%\System32. On 64-bit Windows, 32-bit runtime files use %windir%\SysWOW64. Microsoft also documents application-local deployment, where the runtime sits in the same folder as the application.

The runtime family is separate from DirectX, .NET, and newer Visual C++ packages. Installing a recent Visual C++ package does not automatically replace every older runtime family. Microsoft lists Visual C++ 2010 separately on its legacy Visual C++ Redistributable downloads page.

Error messages caused by mfc100.dll

The wording varies between Windows versions and applications. You may see:

This program can't start because mfc100.dll is missing from your computer.
Try reinstalling the program to fix this problem.

This application failed to start because mfc100.dll was not found.
Re-installing the application may fix this problem.

Cannot find [PATH]\mfc100.dll

The file mfc100.dll is missing.

The code execution cannot proceed because mfc100.dll was not found.
Reinstalling the program may fix this problem.

Some programs report:

mfc100.dll is either not designed to run on Windows or it contains an error.
Try installing the program again using the original installation media or contact
your system administrator or software vendor for support.

That last message does not automatically mean the file is missing. It can indicate a corrupted DLL, a conflicting application-local copy, a dependency problem, or the wrong architecture.

The correct official download

Use Microsoft’s Visual C++ 2010 SP1 Redistributable Package MFC Security Update.

The Download Center page lists:

• vcredist_x86.exe for 32-bit applications;
• vcredist_x64.exe for 64-bit applications;
• vcredist_ia64.exe for Itanium systems.

The IA64 installer is not for ordinary 32-bit or 64-bit Windows PCs.

Microsoft lists the package as version 10.0.40219.325, but different servicing updates, architectures, and locales can result in different file details. Do not treat one version or file size as universal.

Visual C++ 2010 is a legacy runtime and reached the end of extended support on July 14, 2020. The official package remains available, but it should be obtained from Microsoft or supplied by the affected application’s legitimate installer.

Fix 1: Install the matching Visual C++ 2010 package

This is the most likely fix for a genuinely missing mfc100.dll.

Step 1: Check Windows architecture

Open:

Start > Settings > System > About

Under Device specifications, find System type.

This tells you whether Windows itself is 32-bit or 64-bit. It does not necessarily tell you whether the affected application is 32-bit or 64-bit.

Step 2: Identify the application architecture

Use one of these sources:

• the application vendor’s documentation;
• the installer name or download page;
• the application’s support information;
• the executable’s properties if the vendor identifies its architecture there.

A 32-bit application needs the x86 runtime, even when it runs on 64-bit Windows. A 64-bit application needs the x64 runtime.

A 64-bit Windows PC can legitimately need both packages because it may run both 32-bit and 64-bit applications.

Step 3: Download and run the installer

1. Open Microsoft’s Visual C++ 2010 SP1 download page.
2. Select the download button.
3. Choose vcredist_x86.exe or vcredist_x64.exe.
4. Save the installer.
5. Close the affected program.
6. Run the downloaded installer.
7. Accept the license terms and complete setup.
8. Restart Windows.
9. Launch the affected program again.

If the runtime was already installed, the setup program may offer a repair or maintenance option. Use it if available.

If the installer fails

Install pending Windows updates, restart, and run the redistributable again. If Windows reports an access or installation error:

1. Right-click the downloaded installer.
2. Select Run as administrator.
3. Complete the installation.
4. Restart Windows.
5. Test the program again.

Microsoft’s Visual C++ redistributable installation troubleshooting guidance covers failed setup, permissions, Windows servicing, and installation logs.

Fix 2: Repair or reinstall the affected program

The program may have installed an application-local copy of mfc100.dll, or its own prerequisite installation may have been interrupted.

Repair a Windows application

For a compatible Windows 11 application:

1. Open Start > Settings.
2. Select Apps.
3. Select Installed apps.
4. Find the affected program.
5. Select its three-dot menu.
6. Choose Advanced options.
7. Select Repair.

The repair option may not exist for every desktop application.

For a classic desktop program:

1. Open Control Panel.
2. Select Programs > Programs and Features.
3. Right-click the affected application.
4. Select Repair or Change, if available.
5. Follow the installer prompts.
6. Restart Windows and test the program.

Microsoft documents these options in its repair apps and programs instructions.

If repair is unavailable or does not help, uninstall the program and reinstall it using the original installer or the vendor’s current installer. The installer may include the correct Visual C++ prerequisite or an application-local copy that the generic redistributable does not restore.

Do not delete mfc100.dll from an application folder simply because another copy exists in Windows. The program may have been designed to use its local runtime.

Fix 3: Verify a game installation

If the error appears when starting a game, the game’s own launcher may be able to restore a missing or damaged local file.

Epic Games Launcher

1. Open Epic Games Launcher.
2. Select Library.
3. Find the game.
4. Select the three-dot menu beside it.
5. Choose Manage.
6. Select Verify.
7. Wait for the check to finish.
8. Launch the game again.

Verification checks the installed game files and repairs files that are missing or changed. It does not normally affect saved data.

Steam

Open the game’s properties in Steam and use the launcher’s Verify integrity of game files command. Then restart Steam and launch the game again.

If verification completes but the same message returns, install the correct Visual C++ 2010 package separately. The launcher may repair game files without installing an old Windows runtime prerequisite.

Fix 4: Check Windows Security quarantine

If the error began immediately after an antivirus scan, mfc100.dll may have been quarantined.

1. Open Windows Security.
2. Select Virus & threat protection.
3. Select Protection history.
4. Look for an event involving mfc100.dll.
5. Expand the event and inspect its path and source.

Do not restore the file automatically. Restore it only when all of the following are true:

• it came from the official Microsoft redistributable or a trusted application installer;
• its file path belongs to the expected program or runtime location;
• its digital signature and origin are consistent;
• a current security scan does not identify it as malicious.

Microsoft explains the risks of restoring quarantined files in its Protection History documentation.

If Defender has removed the file, reinstall the Microsoft runtime or the affected application instead of copying the quarantined file back manually.

Fix 5: Repair the Visual C++ installation

If Visual C++ 2010 appears to be installed but the application still reports a missing file, repair or reinstall the runtime entry.

1. Open Settings > Apps > Installed apps.
2. Search for Microsoft Visual C++ 2010.
3. Look for the x86 or x64 redistributable entry.
4. Open its menu.
5. Choose Modify, Repair, or the available maintenance option.
6. Complete setup.
7. Restart Windows.

On older Windows interfaces:

1. Open Control Panel.
2. Select Programs > Programs and Features.
3. Select the relevant Microsoft Visual C++ 2010 entry.
4. Choose Change.
5. Select Repair, if offered.
6. Restart Windows.

If repair is not offered or fails, download the matching official package again from Microsoft and reinstall it. Avoid uninstalling every Visual C++ package on the computer. Other applications may depend on different runtime families.

Fix 6: Check for an incompatible local DLL

A file with the correct name can still be wrong for the program.

An application-local copy may be:

• from the wrong architecture;
• damaged;
• from a different servicing level;
• missing its companion runtime files;
• left behind by an older version of the application;
• blocked by security software.

Look in the folder containing the affected application’s executable. If mfc100.dll is there, note its path and compare it with the error message.

Do not replace or rename that copy unless the application vendor specifically instructs you to do so. Some applications require their own local runtime. Others work correctly only after a stale copy is removed or renamed.

The correct next step is usually:

1. Record the application name and version.
2. Record the full path of the executable.
3. Record the full path of every mfc100.dll copy involved.
4. Repair or reinstall the application from its original source.
5. Follow the vendor’s instructions for local runtime files.

Microsoft describes how Windows searches for DLLs and resolves dependencies in its DLL search-order documentation.

Fix 7: Check missing companion dependencies

Sometimes Windows names mfc100.dll, but the real failure is a dependency that mfc100.dll needs.

Check whether the application installation also contains or can obtain related files such as:

• msvcr100.dll;
• msvcp100.dll;
• mfc100u.dll;
• other Visual C++ 2010 runtime files.

Do not download these files individually. Reinstall the matching redistributable or the application so the complete runtime set is restored together.

This is especially important when the message says the DLL is “not designed to run on Windows” or “contains an error.” That wording can indicate an invalid binary or a dependent component failure, not simply a missing file.

Fix 8: Update or reinstall a related driver package

A driver installer or hardware utility may use Visual C++ 2010 even though the driver itself is not the direct source of the error. Reinstall the driver package from the hardware manufacturer and install any prerequisites it documents.

To inspect the device:

1. Right-click Start.
2. Select Device Manager.
3. Expand the relevant category.
4. Right-click the device.
5. Select Properties.
6. Open the Driver tab.
7. Note the provider, date, and version.
8. Select Update Driver if an update is available.

If the problem began immediately after a driver update and Roll Back Driver is available, use that option and restart Windows. For a full reinstall, download the correct package from the hardware vendor before removing the existing device software.

Manually identifying stale drivers can mean checking many devices and matching each package to the correct hardware. Outbyte Driver Updater scans for driver problems and shows what needs attention; the free scan identifies issues, while driver installation is handled by the full version. It is optional, and the hardware vendor’s own driver package remains the preferred source when the error belongs to a specific device utility.

Fix 9: Run DISM and SFC for Windows component corruption

mfc100.dll normally comes from Visual C++ 2010 rather than from the protected Windows component store. Therefore, SFC is not guaranteed to restore it.

Use these commands after checking the redistributable and application installation.

1. Open Start.
2. Type Command Prompt.
3. Right-click Command Prompt.
4. Select Run as administrator.
5. Run:

DISM.exe /Online /Cleanup-Image /RestoreHealth

1. Wait for DISM to complete.
2. Run:

sfc /scannow

1. Wait until the scan reaches 100 percent.
2. Restart Windows.
3. Test the affected program.

Microsoft recommends running DISM before SFC and documents both commands in its System File Checker repair guidance.

If SFC reports that it repaired files, test the application again. If it reports that no integrity violations were found, reinstalling the Visual C++ runtime is still the appropriate path for a missing mfc100.dll.

Repeatedly running SFC and DISM without identifying what changed rarely solves an application-specific runtime problem. Outbyte PC Repair can scan for Windows repair issues and show what needs attention; the free scan reports problems, while repair is performed by the full version. It is optional, and reinstalling the affected program remains the definitive fix when that program owns the broken runtime copy.

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Fix 10: Check Windows Features only when the application requires them

There is no normal Windows Features checkbox that installs mfc100.dll.

Do not enable random features under Turn Windows features on or off as a substitute for installing Visual C++ 2010. DirectX, .NET, and optional Windows components do not supply this MFC runtime file.

Use Windows Features only when the application vendor explicitly says that a particular Windows component is required. Otherwise, focus on the Visual C++ package and the application installer.

Why System32 and SysWOW64 cause confusion

The folder names are counterintuitive on 64-bit Windows:

• %windir%\System32 contains 64-bit system files.
• %windir%\SysWOW64 contains 32-bit system files.

A 32-bit process cannot load a 64-bit DLL. A 64-bit process cannot load a 32-bit DLL.

This is why copying a DLL into a folder based only on its name is unsafe. The correct location depends on the process architecture and the application’s deployment method. Microsoft explains this behavior in its file-system redirector documentation.

Do not choose the redistributable solely from the Windows architecture. Choose it from the application architecture.

Do not download a loose DLL

Avoid websites that offer individual copies of mfc100.dll. A loose download can contain:

• the wrong architecture;
• the wrong Visual C++ revision;
• an outdated or incompatible build;
• missing companion files;
• malware or tampering;
• incorrect permissions;
• a file that creates DLL preloading or search-order risks.

Copying a downloaded DLL into System32, SysWOW64, or the application folder often hides the real problem rather than repairing it.

Use Microsoft’s official redistributable or the application vendor’s installer. Manual replacement is appropriate only when the application vendor supplies the exact signed file and explicitly tells you where to place it.

Why regsvr32 is usually wrong

Do not run this as a general repair:

regsvr32 mfc100.dll

regsvr32 is used for DLLs that expose registration entry points such as DllRegisterServer. It is not a general-purpose tool for repairing runtime files.

With mfc100.dll, the command may produce:

The module "mfc100.dll" was loaded but the entry-point DllRegisterServer was not found.

That message means the registration command does not apply. It does not prove that the file is missing, and it does not repair the Visual C++ installation.

Use regsvr32 only when a software vendor specifically instructs you to register a COM or ActiveX component and provides the correct architecture-specific command. Microsoft documents the command’s purpose in its regsvr32 reference.

Common causes and definitive fixes

Cause	What to do
Visual C++ 2010 is not installed	Install the matching official x86 or x64 redistributable
The wrong architecture is installed	Install x86 for a 32-bit program and x64 for a 64-bit program
The application installation is incomplete	Repair, verify, or reinstall the application
The Visual C++ installation is damaged	Repair or reinstall the relevant redistributable entry
A stale local DLL conflicts with the runtime	Follow the application vendor’s instructions
Antivirus quarantined the file	Verify the source, then reinstall from Microsoft or the vendor
A prerequisite installer failed	Repair the application and rerun the official runtime installer
A driver utility is missing its prerequisite	Reinstall the hardware vendor’s package
Windows components are damaged	Run DISM, then SFC
The failure began after a system change	Scan the device and consider System Restore

If the file exists but the program still fails

Finding mfc100.dll somewhere on the computer does not prove that the application can load it.

Check these items:

1. Read the exact path shown in the error.
2. Check whether the file is beside the application executable.
3. Confirm the application architecture.
4. Install the matching x86 or x64 runtime.
5. Check related files such as msvcr100.dll, msvcp100.dll, and mfc100u.dll.
6. Look for an outdated local copy.
7. Check whether Windows Security or another security product is blocking it.
8. Repair or reinstall the application.
9. Check for an incompatible application manifest.
10. Escalate to the application vendor if the error continues.

The phrase “not designed to run on Windows” does not establish the exact cause by itself. The useful information is the complete message, executable path, DLL path, application architecture, Windows architecture, installed Visual C++ entries, and what changed immediately before the failure.

System Restore for a persistent failure

If the program worked before a recent system change, System Restore may help when a suitable restore point exists.

1. Open Start.
2. Search for Create a restore point.
3. Open it.
4. Select System Restore.
5. Choose a restore point from before the failure.
6. Review the affected programs.
7. Start the restore.

System Restore rolls back system settings and installed programs but normally does not remove personal files. Microsoft describes this and other recovery choices in its Windows recovery options.

Use it only when the timing is clear and a suitable restore point exists. It does not replace reinstalling the correct Visual C++ package.

When to contact the application vendor

Escalate instead of repeatedly replacing DLLs when:

• the correct x86 or x64 runtime is installed;
• the application has been repaired or reinstalled;
• game files have been verified;
• antivirus quarantine has been checked;
• DISM and SFC completed;
• the file exists but produces a load or compatibility error.

Provide the vendor with:

• the complete error text;
• application name and version;
• Windows edition, build, and architecture;
• application architecture;
• executable and DLL paths;
• installed Visual C++ 2010 x86 and x64 entries;
• installer or launcher logs;
• relevant Event Viewer application errors;
• whether the file is digitally signed;
• whether the problem began after an update, cleanup, antivirus event, or reinstall.

A persistent failure may involve an unsupported application, a missing non-MFC dependency, a broken application-local copy, a failed installer, or incompatibility with the current Windows version.

FAQ

Do I need x86 or x64?

Use x86 for a 32-bit application and x64 for a 64-bit application. A 64-bit Windows PC may need both because it can run both kinds of programs.

Is mfc100.dll part of Windows?

It is a Microsoft runtime file, but it is normally supplied by Visual C++ 2010 or by the application that uses it. It is not normally an original core Windows DLL.

Will the newest Visual C++ package fix it?

Not necessarily. Visual C++ 2010 is a separate legacy runtime family. Install the official 2010 package required by the application.

Can I copy mfc100.dll from another computer?

That is not a reliable repair. The other computer may have a different architecture, servicing level, companion files, or application-local deployment. Reinstall the official runtime or the affected application.

Should I put the file in System32?

No. Windows architecture and application architecture determine where the runtime belongs. The installer handles the correct deployment location.

Will DirectX or .NET install mfc100.dll?

No. mfc100.dll belongs to the Visual C++ 2010 runtime family.

Should I run regsvr32?

No, not for ordinary Visual C++ runtime repair. regsvr32 is for DLLs that provide registration entry points, not for every DLL with a .dll extension.

Why does the error appear after an antivirus scan?

The file may have been quarantined, or the program’s installation may already have been damaged. Check Protection History, verify the source, and reinstall the runtime or application rather than restoring an unknown file.

Can SFC restore mfc100.dll?

It may repair protected Windows components, but mfc100.dll normally comes from Visual C++ 2010. SFC is not guaranteed to restore it. Install or repair the matching redistributable first.

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