AWS NICE DCV 'No Session is available~~' Error

hello :) I am a junior cloud developer using AWS. I am using NICE DCV as a product.

When you try to log in to the NICE DCV, a 'No Session~~~' error occurs as shown in the image. Currently, we are creating EC2 with Terraform using code that includes NICE DCV.

Result of asking through Chat GPT

user_data = <<-EOF
              !/bin/bash
              yum install -y https://d1uj6qtbmh3dt5.cloudfront.net/nice-dcv-el7-latest/nice-dcv-release-2023.0-9782.el7.x86_64.rpm
              yum install -y nice-dcv-server
              yum install -y nice-dcv-gl
              systemctl start dcvserver
              systemctl enable dcvserver

              dcv create-session --type virtual --owner ubuntu popcornsar_session
              EOF

It is said that entering the above code will solve the problem, but the same error still occurs.

I would like to resolve the Session Error that occurs every time I connect NICE DCV to EC2. help. If necessary, it would be of great help to me if you could provide specific guidelines and links.

Thank you. :)