I have connected App and added external link of Heroku to show as Canvas App. I have set the location Chatter Tab. In the developer account, my external application is accessible. It has set "Admin approved users are pre-authorized" in Oauth Policies. The external application is visible in Canvas Previewer.
After installing Application in another Salesforce developer account, It shows "App must be invoked via a signed request" in Canvas Previewer., and has "All users may self-authorize" in Oauth Policies. I have gone through this link
Canvas Signed Request not sending refresh_token, and I got an idea that applications should approve by Admin. I am still not sure that is the issue or something else.
Any help would be great !
Thank you ! :)