Not sure it is an IDE issue or Shiny issue.
The shinyapp that I am running was running perfectly till after i created another shinyapp in the same directory (may be that was the cause) for creating a reprex app for stackoverflow.com. The second app did not run and gave the error "connection refused". When I came back to my original app and clicked on
Run App it starts up ok (Listening on http://127.0.0.1:4553) and opens a new window to start the shiny UI and then stops immediately giving an error "Connection Refused". See screenshot.
Interestingly, the shinyapp is running on the shiny server without any interruption. I can see it is running when I visit the IP address through my browser.
My shiny App
Rstudio version: ‘1.3.959’
OS: Ubuntu 16.04
Shiny version: 1.6
What could be going wrong?