What you need to do in order to solve this issue is to change the default app for opening certain types of files, or at least choose a different app from the available ones to open a particular file. Another common occurrence is mix-ups between video players like VLC and Quicktime, with the latter opening files only supported by the former. For Example: Some very frequent culprits of this are archiving apps like Winrar or UnRarX, both of which support very similar file types. What causes this issue most of the time is that you might have two or more apps that support the type of file that you want to open. If you have experienced this issue before and would like to know how to solve it, read along. Most of the time everything will work without issues, but there are other times when your Mac will either not use the ideal app to open a file or will simply not be able to find a suitable app at all. Whenever you double click on any file on your Mac within the Finder, the operating system will by default find the most suitable app to open it and reveal its contents.