What is VFS connection does not exist on AWS C9


I start run server on terminal
and got this when preview


Could you make sure that you’re:

  1. Running the server on (NOTE: this is different from c9.io, which uses
  2. Opening the preview in a browser that currently has the IDE that you’re previewing from open



I am also facing the same issue. On the same browser on which the IDE is open, I am able to open the URL in a new tab, but not able to open it in a different browser or say Postman app. How to do this?




I have the same problem on aws Cloud9


AWS Cloud9’s preview URL requires that you have the IDE open (which establishes the VFS connection) and that you have a session available to what you’re using to access the endpoint that’s logged into the AWS console with access to the IDE. Because of this, we do not recommend using this to test API endpoints or other services which access this endpoint without the ability to log into the AWS console.

Instead, if you want to test an API endpoint, we recommend sharing the app over the internet (rather than through the Preview URL). You can find instructions on how to do this here: https://docs.aws.amazon.com/cloud9/latest/user-guide/app-preview.html#app-preview-share


Hi, I’m not able to preview my code on the rails server for port 8080.
I’ve tried: rails s -b $IP -p $PORT which leads to a VFS Connection Does Not Exist page. I’ve exited the environment, restarted my browser, cleared cookies, booted my instance, and it would work for the first time that I run it, but any subsequent requests to open the rails server again would result in the connection does not exist page. This is highly frustrating and I’ve yet to find any forums/FAQS/resources that addresses this.


I have exactly same issue when I try to rails s -b $IP -p $PORT these days.
I’m not sure when it started but I think it was between the middle and the end of April.

In my case, I also use port 8081 for phpMyAdmin, GUI for mysql on browser.
My rails application and phpMyAdmin both got VFS Connection Does Not Exist.


For the love of god, please just make this a simple one-click set-up option in the Share panel in AWS Cloud9. The configuration article for making the running app publicly viewable is painfully complex!!!