Fix DllUnregisterServer Failed with Error Code 0x80040200

Updated July 2024: Stop getting error messages and slow down your system with our optimization tool. Get it now at this link
  1. Download and install the repair tool here.
  2. Let it scan your computer.
  3. The tool will then repair your computer.

Windows users reported a RegSvr32 “DllUnregisterServer error with error code 0x80040200” when trying to register or unregister a DLL file while installing an application that automatically registers the DLL file.

The detailed RegSvr32 error message looks like this:

Module xxx was loaded, but the call to DllUnregisterServer failed with error code 0x80040200.
You can find more information about this issue online using the error code as your search term.

Cause of the Error

CDO DLLs are used by applications to communicate with databases; B. for reporting and quarantine. Cdosys.dll and cdoex.dll contain commands to access it, but they are slightly different. Programs cannot execute certain commands using the DLL if the registry is incorrect. cdoex.dll is sometimes stored in the registry where cdosys.dll should be located. It is currently unknown why, but there are suspicions that this was due to another program that uses CDO communication (with databases), or that Windows update incorrectly re-saved the records.

Save the file again after installing the program

If you see this error while trying to install the application, most likely it is due to incorrect loading of some dependencies. If so, then to fix the problem, you will most likely need to run the installer with administrator rights, and then manually unregister and register the failed dependency.

  • Open File Explorer and navigate to the installation location causing the error.
  • Right-click it and select “Run as administrator” from the context menu that appears.
  • Follow the instructions on the screen to complete the installation. You don’t mind if you see the same error 0x80040200 – just close the error window and proceed to the next step.
  • Open the Run dialog box by pressing the Windows key + R. Then type “cmd” in the text box and press Ctrl + Shift + Enter to open a command prompt with an extended CMD.
  • In a command prompt terminal, enter the following commands in order, then press Enter after each command to unregister and re-register the OCX dependency:
    • spr32x30.ocx / UNRESIGNED
    • spr32x30.ocx / REGSERVER
  • Restart your computer and see if the problem goes away the next time you start your computer.

July 2024 Update:

You can now prevent PC problems by using this tool, such as protecting you against file loss and malware. Additionally it is a great way to optimize your computer for maximum performance. The program fixes common errors that might occur on Windows systems with ease - no need for hours of troubleshooting when you have the perfect solution at your fingertips:

  • Step 1 : Download PC Repair & Optimizer Tool (Windows 10, 8, 7, XP, Vista – Microsoft Gold Certified).
  • Step 2 : Click “Start Scan” to find Windows registry issues that could be causing PC problems.
  • Step 3 : Click “Repair All” to fix all issues.


Use Administrator Rights to Unregister the DLL File

replace missing DLL files

Step 1. Press Windows Key + R to open the Startup window.

Step 2: Type cmd and press Ctrl + Shift + Enter to open a command prompt with an elevated CMD. Click Yes to grant administrator rights when prompted by User Account Control (UAC).

Step 3: Type the following command and press Enter to manually unregister the DLL file: regsvr32 / u xxx.dll
Note. Replace xxx with the name of the DLL you want to unregister. Example: regsvr32 / u cdo32.dll command.

Step 4: restart your computer.

Run Command Prompt in elevated mode

a. Click Start. Enter cmd into search on startup.

b. Right click cmd.exe and choose if you want to run as administrator.

vs. regsvr32 / u cdo32.dll

re. Check if registration was canceled successfully.

Expert Tip: This repair tool scans the repositories and replaces corrupt or missing files if none of these methods have worked. It works well in most cases where the problem is due to system corruption. This tool will also optimize your system to maximize performance. It can be downloaded by Clicking Here