[RUBY] About the "Oops VFS connection does not exist" error and solution in AWS Cloud9

Introduction

** About the error occurrence situation of "Oops VFS connection does not exist" that occurred during the development of Chapter 1 ** of Rails Tutorial 4th Edition and its solution.

Development environment

• MacOS Catalina 10.15.7
• Safari 13.1.3
• AWS Cloud9
• Rails 5.1.6
• ruby 2.6.3

error contents

Start Rails server on Cloud9 and display the default page from the preview When I try to display it, the following image is displayed. Error message: "Oops VFS connection does not exist"

Cause

Cookies are not required to launch Could9IDE itself, but it seems that ** cookies must be enabled to use the preview function of apps and files **. (Actually, the error message "Third-party cookies disabled" appeared when I first previewed it. You have to look closely at the error message.)

[reference] AWS User Guide Application Preview or File Preview Notification: "Disabled third-party cookies" https://docs.aws.amazon.com/ja_jp/cloud9/latest/user-guide/troubleshooting.html#troubleshooting-preview (January 2, 2021)

solution

In Safari's Preferences> Privacy tab, uncheck ** "Prevent cross-site tracking" **. The default is "on (enabled)". By the way, Safari's "Prevent cross-site tracking" default setting is from version 11.0.

Summary

I felt that it was difficult to find the cause of this time from the error message "Oops VFS connection does not exist", so I wrote this article. When developing on a cloud basis, you also need to pay attention to your browser settings.