How to Fix Mso.dll Not Found or Missing Errors

Mso.dll errors are caused by situations that lead to the removal or corruption of the mso.dll file. This particular DLL file is used by Microsoft programs like Office and Visual Studio, so it's more likely to be seen when using those applications.

In some cases, mso.dll errors could indicate a registry problem, a virus or malware issue, or even a hardware failure.

Mso.dll Errors

There are several ways mso.dll errors can show up on your computer. Here are some of the more common messages you might see:

• Mso.dll Not Found
• This application failed to start because mso.dll was not found. Re-installing the application may fix this problem.
• Cannot find [PATH]\mso.dll
• The file mso.dll is missing.
• Cannot start [APPLICATION]. A required component is missing: mso.dll. Please install [APPLICATION] again.

The context of the error is an important piece of information that will be helpful while solving the problem. The error message most likely appears while using or installing certain programs, or when Windows starts or shuts down. However, as mentioned above, it's most common to see a mso.dll error when using a Microsoft product.

The mso.dll error message could apply to any program or system that might utilize the file on any of Microsoft's operating systems, including Windows 11, Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, and Windows 2000.

How to Fix Mso.dll Errors

Follow these steps in the order they're listed below to address the simpler solutions first.

1. Restore mso.dll from the Recycle Bin. The easiest possible cause of a "missing" mso.dll file is that you've mistakenly deleted it.

   If you suspect this, but you've already emptied the Recycle Bin, you may be able to recover the file with a free file recovery program. Just make sure to do this only if it was working properly before it was deleted (i.e., it wasn't corrupted or malicious).

   Start Windows in Safe Mode to complete any of these steps if you're unable to access Windows normally due to the error.

2. Close out of any unnecessary open programs and try again. Some users have seen the mso.dll error when the system memory is too low to load files properly, effectively fixing the error by closing down any programs or files that aren't needed right now.

   One really easy way to do this is to save your work and then simply restart the computer.

3. Reinstall the program that uses the mso.dll file. If the DLL error occurs when you use a particular program, reinstalling the program should replace the file.

   Or, if the program supports it, repair the installation instead. For example, if you're seeing the mso.dll error in an Office product, open Programs and Features in Control Panel, select the app, and go to Change > Repair.

   Try your best to complete this step. Reinstalling the program that provides the mso.dll file, if possible, is a likely solution to this DLL error.

4. Run a virus/malware scan of your entire system. Some mso.dll errors could be related to a virus or other malware infection on your computer that has damaged the DLL file. It's even possible that the error you're seeing is related to a hostile program that's masquerading as the file.

5. Use System Restore to undo recent system changes. If you suspect that the mso.dll error was caused by a change made to an important file or configuration, System Restore could solve the problem.

6. Update the drivers for hardware devices that might be related to mso.dll. If, for example, you're receiving a "The file mso.dll is missing" error when you play a 3D video game, try updating the drivers for your video card.

   The mso.dll file may or may not be related to video cards—this was just an example. The key here is to pay very close attention to the context of the error and troubleshoot accordingly.

7. Roll back a driver to a previously installed version if errors began after updating a particular hardware device's driver.

8. Run the sfc /scannow System File Checker command to replace a missing or corrupt copy of the mso.dll file. Since this DLL file is provided by Microsoft, System File Checker should restore it.

9. Install any available Windows updates. Many service packs and other patches replace or update some of the hundreds of Microsoft distributed DLL files on your computer. The mso.dll file could be included in one of those updates.

10. Test your memory and then test your hard drive. We've left the majority of hardware troubleshooting to the last step, but your computer's memory and hard drive are easy to test and are the most likely components that might cause mso.dll errors as they fail.

    If the hardware fails any of your tests, replace the memory or replace the hard drive as soon as possible.

11. Repair your installation of Windows. If the individual file troubleshooting advice above is unsuccessful, performing a startup repair or repair installation should restore all Windows DLL files to their working versions.

12. Use a free registry cleaner to repair mso.dll related issues in the registry. A free registry cleaner program may be able to help by removing invalid mso.dll registry entries that might be causing the DLL error.

    We rarely recommend the use of registry cleaners. They are included as an option here as a "last resort" attempt before the destructive step coming up next.

13. Perform a clean installation of Windows. This will erase everything from the hard drive and install a fresh copy of Windows. If none of the steps above correct the mso.dll error, this should be your next course of action.

    All the information on your hard drive will be erased during this step. Make sure you've made the best attempt possible to fix the mso.dll error using a troubleshooting step prior to this one.

14. Troubleshoot for a hardware problem if any mso.dll errors persist. After a clean installation of Windows, your DLL problem can only be hardware related.

Need More Help?

If you're not interested in fixing this problem yourself, see How Do I Get My Computer Fixed? for a full list of your support options, plus help with everything along the way like figuring out repair costs, getting your files off, choosing a repair service, and a lot more.