No connection using Amazon ECS Exec

I am trying to connect to a container using "Amazon ECS Exec", in this way:

but produce this error:

I have the correct role associate to the service in the Task Definition

The role has an inline policy using specific JSON values for resources based on my AWS region, account ID, and cluster name.

And my service has " "enableExecuteCommand": true "

The above using

My task definition has added the following JSON snippet under containerDefinitions to enable ‘initProcessEnabled’:

But despite that, I always get the error at the beginning, I have no connection problems if it can identify that the cluster, the service, the task, and the container with the names and ARN are fine.

What may be the error, thanks.