I took the ID for the extension I created with in the admin UI from the URL and added it to the .env manually  EXTENSION_ID=******** Hope that helps 

I have not solved the problem by creating the .env manually and adding the ID etc.

Hope someone can help. I have an app that needs to be updated to support Theme App extension.  However I am having an issue in that I created a the Theme App Extension in the shopify App admin. The problem now is when I try to update the theme app ex...