Method 1: Solving the DLL Error by Copying the Cdosys.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 "Cdosys.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 "Cdosys.dll" file you extracted and paste it into the "C:\Windows\System32" folder.

   

6. If you are using a 64 Bit operating system, copy the "Cdosys.dll" file and paste it into the "C:\Windows\sysWOW64" as well.

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

   

7. In order to complete this step, you must run the Command Prompt as administrator. In order to do this, all you have to do is follow the steps below.

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

   1. Open the Start Menu and before clicking anywhere, type "cmd" on your keyboard. This process will enable you to run a search through the Start Menu. We also typed in "cmd" to bring up the Command Prompt.
   2. Right-click the "Command Prompt" search result that comes up and click the Run as administrator" option.

   

8. Paste the command below into the Command Line window that opens up and press Enter key. This command will delete the problematic registry of the Cdosys.dll file (Nothing will happen to the file we pasted in the System32 folder, it just deletes the registry from the Windows Registry Editor. The file we pasted in the System32 folder will not be damaged).

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

   

9. If you are using a Windows version that has 64 Bit architecture, after running the above command, you need to run the command below. With this command, we will clean the problematic Cdosys.dll registry for 64 Bit (The cleaning process only involves the registries in Regedit. In other words, the dll file you pasted into the SysWoW64 will not be damaged).

   %windir%\SysWoW64\regsvr32.exe /u Cdosys.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 Cdosys.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 Cdosys.dll file that we deleted.

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

    

12. You may see certain error messages when running the commands from the command line. These errors will not prevent the installation of the Cdosys.dll file. In other words, the installation will finish, but it may give some errors because of certain incompatibilities. After restarting your computer, to see if the installation was successful or not, try running the software that was giving the dll error again. If you continue to get the errors when running the software after the installation, you can try the 2nd Method as an alternative.

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

1. In order to install the dll file, you need to find the file folder for the software that was giving you errors such as "Cdosys.dll is missing", "Cdosys.dll not found" or similar error messages. In order to do that, Right-click the software's shortcut and click the Properties item in the right-click menu that appears.

   

2. Click on the Open File Location button that is found in the Properties window that opens up and choose the folder where the application is installed.

   

3. Copy the Cdosys.dll file.
4. Paste the dll file you copied into the software's file folder that we just opened.

   

5. When the dll file is moved to the software file folder, it means that the process is completed. Check to see if the problem was solved by running the software giving the error message again. If you are still receiving the error message, you can complete the 3rd Method as an alternative.

Method 3: Uninstalling and Reinstalling the Software That Is Giving the Cdosys.dll Error 

1. Press the "Windows" + "R" keys at the same time to open the Run tool. Paste the command below into the text field titled "Open" in the Run window that opens and press the Enter key on your keyboard. This command will open the "Programs and Features" tool.

   appwiz.cpl

   

2. The Programs and Features window will open up. Find the software that is giving you the dll error in this window that lists all the softwares on your computer and "Right-Click > Uninstall" on this software.

   

3. Uninstall the software from your computer by following the steps that come up and restart your computer.

   

4. After restarting your computer, reinstall the software.
5. You can solve the error you are expericing with this method. If the dll error is continuing in spite of the solution methods you are using, the source of the problem is the Windows operating system. In order to solve dll errors in Windows you will need to complete the 4th Method and the 5th Method in the list.

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

1. In order to complete this step, you must run the Command Prompt as administrator. In order to do this, all you have to do is follow the steps below.

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

   1. Open the Start Menu and before clicking anywhere, type "cmd" on your keyboard. This process will enable you to run a search through the Start Menu. We also typed in "cmd" to bring up the Command Prompt.
   2. Right-click the "Command Prompt" search result that comes up and click the Run as administrator" option.

   

2. After typing the command below into the Command Line, push Enter.

   sfc /scannow

   

3. Depending on your computer's performance and the amount of errors on your system, this process can take some time. You can see the progress on the Command Line. Wait for this process to end. After the scan and repair processes are finished, try running the software giving you errors again.

Method 5: Getting Rid of Cdosys.dll Errors by Updating the Windows Operating System 

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.

Windows Update Guides 

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