Method 1: Installing the Extension.dll File to the Windows System Folder 

1. The file you downloaded is a compressed file with the extension ".zip". This file cannot be installed. To be able to install it, first you need to extract the dll file from within it. So, first double-click the file with the ".zip" extension and open the file.
2. You will see the file named "Extension.dll" in the window that opens. This is the file you need to install. Click on the dll file with the left button of the mouse. By doing this, you select the file.

   

3. Click on the "Extract To" button, which is marked in the picture. In order to do this, you will need the Winrar software. If you don't have the software, it can be found doing a quick search on the Internet and you can download it (The Winrar software is free).
4. After clicking the "Extract to" button, a window where you can choose the location you want will open. Choose the "Desktop" location in this window and extract the dll file to the desktop by clicking the "Ok" button.

   

5. Copy the "Extension.dll" file you extracted and paste it into the "C:\Windows\System32" folder.

   

6. If your operating system has a 64 Bit architecture, copy the "Extension.dll" file and paste it also into the "C:\Windows\sysWOW64" folder.

   NOTE! On 64 Bit systems, the dll file must be in both the "sysWOW64" folder as well as the "System32" folder. In other words, you must copy the "Extension.dll" file into both folders.

   

7. First, we must run the Windows Command Prompt as an administrator.

   NOTE! We ran the Command Prompt on Windows 10. If you are using Windows 8.1, Windows 8, Windows 7, Windows Vista or Windows XP, you can use the same methods to run the Command Prompt as an administrator.

   1. Open the Start Menu and type in "cmd", but don't press Enter. Doing this, you will have run a search of your computer through the Start Menu. In other words, typing in "cmd" we did a search for the Command Prompt.
   2. When you see the "Command Prompt" option among the search results, push the "CTRL" + "SHIFT" + "ENTER
   " keys on your keyboard.
   3. A verification window will pop up asking, "Do you want to run the Command Prompt as with administrative permission?" Approve this action by saying, "Yes".

   

8. Let's copy the command below and paste it in the Command Line that comes up, then let's press Enter. This command deletes the Extension.dll file's problematic registry in the Windows Registry Editor (The file that we copied to the System32 folder does not perform any action with the file, it just deletes the registry in the Windows Registry Editor. The file that we pasted into the System32 folder will not be damaged).

   %windir%\System32\regsvr32.exe /u Extension.dll

   

9. If you are using a 64 Bit operating system, after doing the commands above, you also need to run the command below. With this command, we will also delete the Extension.dll file's damaged registry for 64 Bit (The deleting process will be only for the registries in Regedit. In other words, the dll file you pasted into the SysWoW64 folder will not be damaged at all).

   %windir%\SysWoW64\regsvr32.exe /u Extension.dll

   

10. We need to make a new registry for the dll file in place of the one we deleted from the Windows Registry Editor. In order to do this process, copy the command below and after pasting it in the Command Line, press Enter.

    %windir%\System32\regsvr32.exe /i Extension.dll

    

11. If the Windows version you use has 64 Bit architecture, after running the command above, you must run the command below. With this command, you will create a clean registry for the problematic registry of the Extension.dll file that we deleted.

    %windir%\SysWoW64\regsvr32.exe /i Extension.dll

    

12. If you did all the processes correctly, the missing dll file will have been installed. You may have made some mistakes when running the Command Line processes. Generally, these errors will not prevent the Extension.dll file from being installed. In other words, the installation will be completed, but it may give an error due to some incompatibility issues. You can try running the program that was giving you this dll file error after restarting your computer. If you are still getting the dll file error when running the program, please try the 2nd method.

Method 2: Copying the Extension.dll File to the Software File Folder 

1. First, you need to find the file folder for the software you are receiving the "Extension.dll not found", "Extension.dll is missing" or other similar dll errors. In order to do this, right-click on the shortcut for the software and click the Properties option from the options that come up.

   

2. Open the software's file folder by clicking on the Open File Location button in the Properties window that comes up.

   

3. Copy the Extension.dll file into this folder that opens.

   

4. This is all there is to the process. Now, try to run the software again. If the problem still is not solved, you can try the 3rd Method.

Method 3: Doing a Clean Reinstall of the Software That Is Giving the Extension.dll Error 

1. Push the "Windows" + "R" keys at the same time to open the Run window. Type the command below into the Run window that opens up and hit Enter. This process will open the "Programs and Features" window.

   appwiz.cpl

   

2. The Programs and Features screen will come up. You can see all the softwares installed on your computer in the list on this screen. Find the software giving you the dll error in the list and right-click it. Click the "Uninstall" item in the right-click menu that appears and begin the uninstall process.

   

3. A window will open up asking whether to confirm or deny the uninstall process for the software. Confirm the process and wait for the uninstall process to finish. Restart your computer after the software has been uninstalled from your computer.

   

4. After restarting your computer, reinstall the software that was giving the error.
5. This process may help the dll problem you are experiencing. If you are continuing to get the same dll error, the problem is most likely with Windows. In order to fix dll problems relating to Windows, complete the 4th Method and 5th Method.

Method 4: Solving the Extension.dll Error using the Windows System File Checker (sfc /scannow) 

1. First, we must run the Windows Command Prompt as an administrator.

   NOTE! We ran the Command Prompt on Windows 10. If you are using Windows 8.1, Windows 8, Windows 7, Windows Vista or Windows XP, you can use the same methods to run the Command Prompt as an administrator.

   1. Open the Start Menu and type in "cmd", but don't press Enter. Doing this, you will have run a search of your computer through the Start Menu. In other words, typing in "cmd" we did a search for the Command Prompt.
   2. When you see the "Command Prompt" option among the search results, push the "CTRL" + "SHIFT" + "ENTER
   " keys on your keyboard.
   3. A verification window will pop up asking, "Do you want to run the Command Prompt as with administrative permission?" Approve this action by saying, "Yes".

   

2. Paste the command below into the Command Line that opens up and hit the Enter key.

   sfc /scannow

   

3. This process can take some time. You can follow its progress from the screen. Wait for it to finish and after it is finished try to run the software that was giving the dll error again.

Method 5: Fixing the Extension.dll Error by Manually Updating Windows 

Most of the time, softwares have been programmed to use the most recent dll files. If your operating system is not updated, these files cannot be provided and dll errors appear. So, we will try to solve the dll errors by updating the operating system.

Since the methods to update Windows versions are different from each other, we found it appropriate to prepare a separate article for each Windows version. You can get our update article that relates to your operating system version by using the links below.

Guides to Manually Update for All Windows Versions 

1. Guide to Manually Update Windows 10
2. Guide to Manually Update Windows 8.1 and Windows 8
3. Guide to Manually Update Windows 7 and Windows Vista
4. Guide to Manually Update Windows XP