I use Ubuntu 18.04 Bionic Beaver LTS and OpenJDK (runtime version 11 and 8) as an application that executes java executables. However, when I try to open the jar file, the launcher to be more exact, it gives me this error:
The file '/home/hag/Downloads/ccemuredux-launcher.jar' is not marked as executable. If this was downloaded or copied from an untrusted source, it may be dangerous to run.
When I click ok or close the window, it does nothing as well.