How to Fix error: unable to upgrade connection: container not found

A Docker container is a lightweight, standalone, and executable package that contains everything an application needs to run, including the application code, libraries, dependencies, and runtime.

Let’s discuss an error related to the docker container and how to fix it.

I faced this error, and I tried various solutions that helped me solve the issue. Let me share it with you guys!

error: unable to upgrade connection: container not found

The error: unable to upgrade connection: container not found occurs when you try to connect to a Docker container that does not exist or is not running.

Causes of the error

  1. The error “The container specified in the connection upgrade request does not exist” means that you are trying to connect to a Docker container that does not exist or is not running.
  2. The error “The container has been deleted or is in a stopped state” implies that you are trying to connect to a Docker container that does not exist or is not running.
  3. There may be other reasons, like the containers crashing. For example, you can check logs of the containers/events of the pods or containers hasn’t been started yet.

How to fix error: unable to upgrade connection: container not found

  1. You need to make sure that your docker container is running. You can check the list of running containers using the “docker ps” command.
  2. You must ensure that the container name or ID you use is correct. Then, use the “docker ps -a” command to see a list of all containers, including stopped ones.
  3. Try connecting to the container using the “docker exec” command. For example, the “docker exec -it <container_name_or_id> /bin/bash” command will open a shell inside the container, allowing you to solve any issues.
  4. If the system still cannot find a container, there may be a problem with the Docker daemon. Restart the Docker daemon using the “sudo service docker restart” command.

FAQs

What is the unable to upgrade connection: container not found error?

The unable to upgrade connection: container not found error notice is shown on the screen when you are trying to connect to a Docker container that does not exist or is not running.

What should I do if the unable to upgrade connection: container not found error persists?

After applying all of the above solutions, If the error persists, there may be a more severe problem with the Docker daemon or the container itself. Try installing everything on a different system and see if the error is there in the new system.

That’s it for this tutorial.

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