Then check its contents. In fact, it's the only file that associates an icon with the application.
It should look like this:
Particularly, pay attention to the Exec line: --type=d should be present only if your project was created as "boostable", otherwise delete it. And make sure that this line points to your actual deployment path, e.g. here it's /opt/yourapp
Exec=/usr/bin/invoker --type=d -s /opt/yourapp/bin/yourapp