How do I fix "mscorlib.dll is missing" error?

Repair or reinstall the .NET Framework. Go to Windows Settings > Apps > Optional Features and ensure .NET Framework is installed. You can also download the .NET Framework Repair Tool from Microsoft.

Is it safe to download mscorlib.dll?

Yes, when downloaded from official sources. We recommend installing the official .NET Framework 4.8 package instead of downloading individual DLL files. This ensures you get a digitally signed, verified file directly from Microsoft.

Where should I put mscorlib.dll?

For 64-bit applications, place in C:\Windows\System32. For 32-bit applications on 64-bit Windows, place in C:\Windows\SysWOW64. However, we strongly recommend using the official installer instead of manual placement.

.NET Framework Version 4.8.4761.0

Fix mscorlib.dll Missing Error

Scanned: 2025-11-30

MD5 Verified

0.3M+ downloads

⚡ Quick Fix: Install .NET Framework 4.8

This is the recommended fix from Microsoft. It will restore mscorlib.dll and all related runtime files automatically.

Download Official Package From Microsoft.com

Common Error Messages

✗ mscorlib.dll error

✗ Could not load type

What is mscorlib.dll?

Mscorlib.dll is the core .NET Framework class library containing fundamental types like System.String, System.Object, and System.Collections.

How to Fix "mscorlib.dll is missing" Error

1 Method 1: Run System File Checker

sfc /scannow

Open Command Prompt as Administrator and run this command. It will scan and repair corrupted system files.

2 Method 2: DISM Repair

DISM /Online /Cleanup-Image /RestoreHealth

If SFC doesn't work, run this command to repair the Windows image.

Manual Download (Last Resort)

⚠️ Important Warning

Downloading individual DLL files is not recommended. We strongly advise using the official runtime package above. Only use manual download if the official method fails.

If you must manually place the file:
• 64-bit apps: C:\Windows\System32
• 32-bit apps on 64-bit Windows: C:\Windows\SysWOW64