Error message "Incompatible with the current WebStorm version." while installing plugin but plugin install successfully

I'm using a Custom Plugin Repository.

1. Go to the Marketplace tab.
2. Install the plugin.
3. While it's still downloading, click on the Installed tab. I see that there's an error message "Incompatible with the current WebStorm version.".
   
4. Plugin install successfully.
5. After restart, the plugin is working.

Why is the error message appearing during download/installation when the plugin actually is compatible and installed properly?