F-Secure Booster did not open due to missing mfc120u.dll

I have been using F-S Booster since 21.10.2015. Yesterday (23 Feb) , perhaps in connection with a Windows 10 routine update, I could not open the Booster due to error message "missing mfc120u.dll" advising to reinstall the program. What is this missing "dll" needed for and why was it lost?


After this mishap I have today reinstalled the F-S Booster (version which looks better than the previous version I had. Seems 120 days of usage remain of my licence. Unfortunately, I cannot find other details of my original licence for the Booster. Any help from F-Secure?


  • LakshLaksh Posts: 4,444 Community Manager

    Hi Bulbhead,


    Was the missing dll error message came from Windows or from the Booster program? A screenshot might be helpful in this case.


    You could see your subscription key here: Open the program > On the left, click About> You should see the subscription key in there. Are you able to find it?


    Alternatively, if you just need your subscription key details (not only from the product), you will also have it in your email which you used during the purchase.

  • The error message was from the Booster program which refused to start. The program works as it should after reinstallation. I did find the subscription key under "About" and could verify that there are still about 4 months left of this subscription. Good that I did, since I had deleted the original email concerning this subscription.

  • LakshLaksh Posts: 4,444 Community Manager

    Hi Bulbhead,


    Good to know the reinstallation resolved the issue. If the purchase was made from F-Secure directly, you can always contact our Support via chat or Email and they should be able to get the subscription details for your Booster product.

This discussion has been closed.