Step 1: Select and download the DLL files from the table below irrespective of the version of your OS i.e. Windows 11, 10, 8.1, 8 or 7.,

Step 2: Once downloaded, extract each file into separate folders using either Windows Compressed folders (comes with windows) or with an app like WinRAR.

Step 3: Next, copy the 64-bit 'OSUNINST.DLL' file and paste it into the C:\Windows\System32 folder. And copy the 32-bit 'OSUNINST.DLL' file and paste it into the C:\Windows\SysWOW64 folder. If there is an existing 'OSUNINST.DLL' file in either of these folders then replace it with the new file. However, if you have a 32-bit Windows system then place only the 32-bit file into the C:\Windows\System32 folder.

Re-launch the affected program to see if the issue is fixed. If not, please try the next method.

Step 1: Download the installation file from here.

Step 2: Install PC Repair and scan your PC

Step 3: Click 'Repair' to fix all items that may cause the missing DLL errors.

Step 4: Launch the application to see if the error is fixed.

Step 1: Launch the Run utility by pressing Windows + R keys on your keyboard. Type in 'cmd' in the text input field. Then press Ctrl+Shift+Enter keys to open the Command Prompt in administrator mode.

Step 2: In the prompt window, select 'Yes' to allow Command Prompt to make modifications to your device.

Step 3: Now it's time to unregister the DLL file from your computer. Type in or copy and paste the following command, then press Enter,

regsvr32 /u OSUNINST.DLL

Note: Replace vcruntime140.dll with OSUNINST.DLL

Step 4: Next, you need to re-register the file. To do this run the following command,

regsvr32 OSUNINST.DLL

Note: Replace vcruntime140.dll with OSUNINST.DLL

Step 5: Exit the Command Prompt and run the application again.

Step 1: To access the official page from where Microsoft Visual C++ Redistributable can be downloaded, please click on the link provided here

Select 'Install'. The installation will begin and will take a couple of seconds to complete.

Step 2: Alternatively, you can also download it from below based on the version of Windows,

Download x86 version from here

Download x64 version from here

Step 3: Once you've selected the file, proceed to download. The download may take a while, depending on your internet connection speed.

Step 4: Once the download is complete install the downloaded file. When the installation begins tick the 'I agree to the license terms and conditions' box and then click on 'Install'.

Step 5: It may take a few minutes for the installation to finish. Once the installation is completed restart the computer and launch the program again to see if the DLL error is fixed.

Step 1: To open the Run utility, press Windows + R on your computer. Enter 'cmd' in the input area and then press Ctrl+Shift+Enter.

Step 2: Select 'Yes' in the pop-up window to open the command prompt in administrator mode.

Step 3: Next, enter the below command and press Enter to execute it,

sfc/scannow

Step 4: This command will try to search and fix corrupt system files (including DLL files). Once the process is complete, you can check the log file created in the path shown in the command prompt. If in the log file you find details of the fixed DLL File then you can run the application again.

Step 1: Open Control Panel and click on 'Uninstall a program' under 'Programs'.

Step 2: Search and find the program you're experiencing problems with and click on it.

Step 3: Then click on the 'Uninstall' button, and proceed to continue with the uninstallation procedure of the application.

Step 4: Reinstall the program from its source. Either download the setup file or if you already have it then run the installation again to check if you can run the application this time.

Method 1: Automatically Update Drivers

Step 1: Use a tool like Outbyte Driver Updater that automatically searches for missing and out dated drivers in your system and updates it. You can download the tool from here

Step 2: Download time depends on your internet speed connection. Once the download is completed start with the installation of the tool.

Step 3: Launch the application.

Step 4: Inside the application run update. Then, the Driver Updater tool will scan your computer for out dated and missing drivers.

Step 5: Finally, select the drivers and click update.

Method 2: Manually Update Drivers

Step 1: Go to the Taskbar search box – enter the text Device Manager and select Device Manager.

Step 2: Select the hardware device that needs to be updated. Expand the selection – select the device, right-click and select 'Update Driver'.

Step 3: Choose the 'Search automatically for drivers' option.

Step 4: If the latest drivers are found then they will be installed automatically.

Step 5: Sometimes, Windows might not be able to find the latest driver. In such cases, the user can visit the manufacturer's website, search for the driver, and instructions on how to proceed with the installation.

Step 1: Begin by clicking on the start button.

Step 2: To access the System Properties window, search for 'Create a restore point' and click the first result.

Step 3: Under the 'System Protection' tab select the 'System' drive. 'Protection' should be turned on for this drive.

Step 4: Select 'System Restore' and click 'Next' on the initial screen

Step 5: A list of restore points will be displayed. Select the restore point when your application was running correctly without any error. Then select 'Next'.

Step 6: Review your selection and click 'Finish'. If a warning window pop-up appears then select Yes'.

Step 7: The System Restore will begin and your PC will restart once the process is complete. When you log in again, you will see a notification that the System Restore is complete. Now, you can run the application again to see if the error is fixed.

Note: If System Restore was not set up earlier or you've never backed up your PC before then this method might not apply to you.

Step 1: Go to settings by selecting Start > Settings or using Windows + I shortcut

Step 2: Open the 'Update and security' option.

Step 3: See if there are any new updates by clicking on 'Check for updates.'

Step 4: If a newer version is discovered, then the windows update will download and install to the latest version.

Step 5: After installing the newest version, run the program again to check if you face the OSUNINST.DLL was not found error.