Unable to start the environment. To retry, refresh the browser or restart by selecting Actions, Restart AWS CloudShell

I am unable to use aws cloud shell. I operate in the supported region (Ireleand) and my user has the right permissions (AWSCloudShellFullAccess).

{ "Version": "2012-10-17", "Statement": [ { "Action": [ "cloudshell:*" ], "Effect": "Allow", "Resource": "*" } ] }

Why is it disabled?

I tried to follow this guide. But the advice there doesnt work. AWS cloudshell troubleshooting

Solution

So i was able to resolve this issue. Few things to try to create CloudShell environment:

Time Synchronization: Make sure Your machine time is accurate. It means its correct based on world time. did you try from another machine to see if its working there? may be any time sync related issue?
Check in different regions..
check AWSCloudShellFullAccess policy to ensure it has below JSON data.

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Action": [
                "cloudshell:*"
            ],
            "Effect": "Allow",
            "Resource": "*"
        }
    ]
}

Check in different browser to see if it works in different browser or not. https://docs.aws.amazon.com/cloudshell/latest/userguide/troubleshooting.html
Did you deleted cloudshell home directory or something? Try after resetting home directory. But it can DELETE all your data exists in home directory. https://docs.aws.amazon.com/cloudshell/latest/userguide/vm-specs.html#deleting-home-directory
check if any DENY policy created for it. remove that.
It is possible your account is not 100% verified. Try this: Create a CloudFront distribution if you get the below error it confirms your account is unverified or if you can create 2 distributions and can't create the 3rd one.

Your account must be verified before you can add new CloudFront resources. To verify your account, please contact AWS Support (https://console.aws.amazon.com/support/home#/ ) and include this error message.

Click the support link

Navigate to: Support / New case / Service limit increase
Limit type: CloudFront Distributions
In Requests select: Limit: Web Distributions per Account New limit value: <TYPE_YOUR_NEW_VALUE_HERE>

MY CASE: In my case, I had 2 distributions, wanted to create 3rd, but couldn't. So I have put as <TYPE_YOUR_NEW_VALUE_HERE> a number 10.

Note: If nothing works choose last option as your last resort to confirm your account is verified.