vcomp100.dll is missing - fix it the right way

vcomp100.dll is the OpenMP library from the Microsoft Visual C++ 2010 runtime. Programs and games built with the 2010 toolset - and there are still plenty of them - load it at startup. Having the newest Visual C++ runtime does not help here: the 2010 runtime is a separate, older package that installs alongside the new ones. The safe fix takes about two minutes.

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Quick answer

Download the Microsoft Visual C++ 2010 Redistributable from microsoft.com (search "Visual C++ 2010 SP1 Redistributable"), install both the x86 and x64 packages, and restart the PC. The 2010 runtime installs side by side with newer runtimes - nothing gets replaced or broken.

Symptoms - how this problem looks

"The program can't start because vcomp100.dll is missing"

An older game, converter or engineering tool fails right at launch

It happens on a freshly installed or freshly "cleaned" Windows

Newer programs on the same PC run without complaints

The message returned after removing an unrelated old program

A similar message names vcomp110.dll, vcomp120.dll or vcomp140.dll

Why it happens

The 2010 runtime was never installed

A fresh Windows has no Visual C++ 2010 runtime - it always arrived with some program's installer. Until an old-school program brings it, the file is absent.

Newer runtimes do not include it

Visual C++ runtimes stopped being cumulative after 2013: the 2015-2022 package covers only 2015 and newer. 2010 is its own separate install, by design.

An uninstaller took it along

Removing an old program can remove the shared 2010 runtime that another old program still needs - the error appears in the survivor.

The runtime got damaged

Disk errors or an overzealous cleanup tool corrupted the runtime files that several programs share - repair or reinstall brings them back.

The fixes, in order

1. Install the Visual C++ 2010 Redistributable (fixes most cases)

Search the web for "Visual C++ 2010 SP1 Redistributable" and open the result on microsoft.com - Microsoft's official download page.
Download both packages: the x86 one and the x64 one.
Run both installers.
Restart the PC and launch the failing program.

2. Repair the 2010 runtime if it is already listed

Open Settings, then Apps, then Installed apps.
Search for "Microsoft Visual C++ 2010" - you may see an x86 and an x64 entry.
Select each, press Modify (or Uninstall, then reinstall fresh from method 1).
Restart and test.

3. Reinstall the failing program

If only one program shows the error, uninstall it in Settings, then Apps.
Download a fresh installer from the developer's official site and reinstall - old installers usually carry the 2010 runtime with them.
For Steam games: right-click the game, Properties, Installed Files, then "Verify integrity of game files".

Do not do this: Never download vcomp100.dll as a single file from a "DLL download" site. A lone copy is often the wrong build, breaks other programs, and such sites are a classic malware channel. The official 2010 Redistributable is free and restores every related file correctly.

Cheat sheet - which download fixes which vcomp DLL

The error names	What it belongs to	The fix
vcomp100.dll	Visual C++ 2010 runtime	Visual C++ 2010 SP1 Redistributable, x86 + x64 (method 1)
vcomp110.dll	Visual C++ 2012 runtime	Visual C++ 2012 Redistributable from microsoft.com
vcomp120.dll	Visual C++ 2013 runtime	Visual C++ 2013 Redistributable from microsoft.com
vcomp140.dll	Visual C++ 2015-2022 runtime	vc_redist x64 + x86 - see the VCRUNTIME140 guide
vcomp90.dll	Visual C++ 2008 runtime	Visual C++ 2008 SP1 Redistributable from microsoft.com

Frequently asked questions

I already have the newest Visual C++ 2015-2022 runtime. Why is vcomp100.dll still missing?

Because the 2010 runtime is a separate install. Visual C++ runtimes are not cumulative: 2015-2022 replaced only 2015 and newer. A program built with Visual C++ 2010 needs exactly the 2010 Redistributable, side by side with any newer ones.

Do I need the x86 version, the x64 version, or both?

Install both. A 32-bit program loads the x86 runtime even on 64-bit Windows, and you rarely know which flavor the failing program is. Both installers are small and coexist without conflict.

The error names vcomp110.dll or vcomp140.dll instead. Which download fixes those?

The number tells the year: vcomp110 needs the Visual C++ 2012 Redistributable, vcomp120 the 2013 one, and vcomp140 comes with the 2015-2022 package. Each is a free official download from Microsoft - the cheat sheet above maps them all.