mscoree.dll not found or failing: how to fix the .NET Framework error

Each file below is Microsoft's own mscoree.dll for one Windows release, fetched from Microsoft's own server and checked against Winbindex, the index of the files in Windows images and updates. Use these files to compare: to confirm that a mscoree.dll you have is genuine, or to see which build your release should have. Copying one into a program folder does not fix a .NET error, because the runtime behind the file is what the program needs. Windows' own copy is repaired with the steps above.

A free uGetFix account is needed to download. Sign in, or create one in a minute, and you come straight back here.

The wording tells you which part failed: the loader file, the runtime it looks for, or the program after it started. These are the texts people see, with the program name left out.

mscoree.dll describes itself as Microsoft .NET Runtime Execution Engine. Programs written for .NET Framework are not ordinary Windows programs: their .exe files contain .NET code that Windows hands to mscoree.dll at start. The file reads which .NET Framework version the program targets, finds that runtime and starts it, and from then on the program runs inside the runtime. It is a shim, a thin front door, which is why one copy serves every installed .NET Framework version. What Windows reports for the genuine file:

On 64-bit Windows, System32 holds the 64-bit file and SysWOW64 the 32-bit one used by 32-bit .NET programs; the folder names are historical. The runtime itself lives elsewhere, in C:\Windows\Microsoft.NET\Framework and Framework64, where mscoreei.dll, the version-specific part of the loader, sits in each runtime's own folder. In Windows 11 24H2 and 25H2 the 64-bit mscoree.dll is 430,080 bytes and the 32-bit file 327,168 bytes; in Windows 10 22H2 they are 383,488 and 314,880 bytes. Windows signs the file through a catalog, so Properties may show no Digital Signatures tab even on the genuine copy.

Every Windows release has its own build of mscoree.dll. Unlike most system files, it changes rarely: many releases still carry the build from their first image. Winbindex lists 31 distinct Microsoft builds; the table shows the newest one indexed for each release and the update that delivered it.

Public DLL catalogues have collected 16 copies of mscoree.dll uploaded from PCs, from version 1.0.3705.0 to 10.0.14393.0. The 1.x, 2.x and 4.x numbers come from .NET Framework installers for Windows XP, Vista and 7, when the file was installed with .NET Framework instead of with Windows. The table lists each with its checksums, so you can tell which one you have.

None of these replaces the file your Windows ships: the newest build indexed for Windows is 10.0.28000.1896, and each release keeps its own. If the check on this page finds your file in this list, it is most likely an old copy left in a program folder or downloaded by hand. Remove the copy, and let Windows use its own.

Copies uploaded by users to a public DLL catalogue, read on 17 October 2026. We list their checksums so you can identify a file; we do not offer them for download and we did not verify each one against Microsoft's signature.