How can solve this issue, on a macbook?

Hello!

In the error, I see:

Caused by: com.intellij.platform.instanceContainer.internal.InstanceAlreadyRegisteredException: com.tang.intellij.lua.project.LuaSettings

It's caused by the EmmyLua plugin. Please remove the plugin's folder or .jar file from the IDE plugins' directory - after that, you should be able to start IDE without the problems.

Hello! 

Thanks for the hint. There's no file called JetBrains nor Clion in the directory “Library/Application Support/ Jetbrains” mentioned in this link IDE plugins' directory . However, I have tried to deinstall and then install Clion again on my machine, didn't affect the error. I also tried to find the Lua plug-in within Library/Preferences and  Library/Cache, also in vain. 

Any hints?

have tried to deinstall and then install Clion again on my machine

Uninstallation doesn't remove the IDE settings, that's why it didn't help.

There's no file called JetBrains nor Clion in the directory “Library/Application Support/ Jetbrains”

Could you please double-check the ~/Library/Application Support directory mentioned in the web help? Please mind ~ at the beginning of the path. It means /Users/<user_name>.

Hi, I've just double-checked, this time by using the terminal to navigate through the folders instead of the Mac's Files Explorer: Finder. I've finally found the Lua plugin and deleted it.  

Many thanks to you!