Error: could not connect to the endpoint URL dynamodb

Could not connect to the endpoint URL means the SDK could not reach the configured service endpoint. An account mismatch normally produces a service response, not a TCP connection failure.

1. Inspect endpoint_url or endpoint overrides. For real AWS, prefer the SDK's Region-based endpoint unless a specific endpoint is required.
2. Check DNS resolution, firewall, proxy and VPC routing from the process that failed. Private workloads need a working path through an endpoint or NAT as appropriate.
3. For DynamoDB Local, confirm the server is running, the port is published and the client uses HTTP with the correct port.
4. Inside Docker, localhost means the current container. Use the database service name on a shared network; use the published host port from the host.

AWS_ACCESS_KEY_ID=local AWS_SECRET_ACCESS_KEY=local \
aws dynamodb list-tables --region us-east-1 \
  --endpoint-url http://localhost:8000

The dummy credentials above are only for the explicit local endpoint. If the connection succeeds and the error changes to access denied, diagnose permissions next. Do not disable TLS certificate validation to bypass an unrelated connection problem.

See local endpoint setup and AWS documentation.