Computers Files

How to Fix Mfc100u.dll Not Found or Missing Errors in Windows

The mfc100u.dll file is associated with the Microsoft Visual C++ framework and is used by a variety of software applications. A missing or corrupted mfc100u.dll file can cause errors and prevent some programs from running properly. Here’s a comprehensive guide on how to address these errors:

1. Restart Your Computer:

A simple restart can sometimes resolve DLL errors. It’s a basic step, but always worth trying first.

2. Reinstall the Problematic Application:

If a specific program is showing the mfc100u.dll error, try reinstalling that application:

  1. Go to “Control Panel” > “Programs and Features.”
  2. Locate the problematic application, right-click on it, and select “Uninstall.”
  3. Restart your computer.
  4. Reinstall the application by downloading it from the official website or using the installation disc.

3. Install/Reinstall Microsoft Visual C++ Redistributable:

The mfc100u.dll file is a part of the Microsoft Visual C++ 2010 Redistributable Package.

  1. Go to the official Microsoft download page for Visual C++ 2010 Redistributable.
  2. Download the package suitable for your system (x64 for 64-bit systems and x86 for 32-bit systems).
  3. Run the installer and follow the prompts.
  4. Restart your computer after the installation.

4. Check the Recycle Bin:

You might have accidentally deleted the DLL file. Check the Recycle Bin, and if the mfc100u.dll file is there, right-click and choose “Restore.”

5. Run a Malware/Virus Scan:

Malicious software can sometimes cause issues with DLL files. Run a full system scan using a reputable antivirus or anti-malware program.

6. Use System File Checker:

The System File Checker (SFC) tool can identify and fix corrupted or missing system files:

  1. Open Command Prompt as an administrator.
  2. Type sfc /scannow and press Enter.
  3. Wait for the scan to complete. If any issues are found, the tool will try to fix them.

7. Update Windows:

Microsoft regularly releases updates and patches for Windows. Ensuring your system is up-to-date might resolve the missing DLL issue:

  1. Go to “Settings” > “Update & Security.”
  2. Click on “Check for updates.”
  3. Install any available updates and restart your computer.

8. Manually Download and Replace the DLL File:

Caution: This method is risky and not generally recommended because downloading DLL files from unofficial websites can harm your computer or introduce malware. Only do this if you’re sure of the source.

  1. Download the mfc100u.dll file from a trusted source.
  2. Place the file in C:\Windows\System32 (for 32-bit systems) or C:\Windows\SysWOW64 (for 64-bit systems).

9. Restore Your System:

If the error started appearing recently, use the System Restore feature to restore Windows to a previous state:

  1. Type “create a restore point” into the Windows search bar and select the corresponding result.
  2. In the “System Properties” window, click on the “System Restore” button.
  3. Follow the prompts to restore your system to a state before the error began appearing.

10. Perform a Clean Installation of Windows:

As a last resort, if all the above methods fail, consider performing a clean install of Windows. This method will delete all data and applications on your system, so ensure you back up essential files beforehand.


Resolving mfc100u.dll not found or missing errors requires a systematic approach. Always prioritize safer methods, such as using built-in Windows tools or official software, before opting for riskier solutions like manually downloading DLL files.

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