After upgrading to macOS Catalina, some Mac users reported that some apps can’t be opened because Apple cannot check it for malicious software. A dialog box appears, when clicking on "OK" button the application will close.

If you get this prompt opening the app. How to fix it?

First try downloading the app again from our download page. The app file may be damaged or out of date. Replace the old version with the one you just downloaded and try again.

If it didn't work, follow these simple steps:

  1. Check whether there are other copies of that particular app in your hard drive, and eventually delete them. The only copy of the app has to be in the Applications folder.
  2. Control-click the app to get the contextual menu and choose the item "Open".
  3. In the warning box that appears, click on Open button.

Subsequent times, the app will work properly.

Related online resources

  1. How to fix that app can't open on macOS Catalina?
  2. Open a Mac app from an unidentified developer [Apple]