No endpoint for as2 sender id for as2 receiver id at this path

The error message you're receiving, "No endpoint for as2 sender id for as2 receiver id at this path," suggests that there might be a mismatch or configuration issue with the AS2 identifiers or the endpoint URL.

Given that you've already checked the profiles, certificates, connector, and agreement, and confirmed that the URL matches the Amazon-hosted AS2 server URL, there are a few things to consider:

1. Double-check that the AS2-From and AS2-To identifiers in your connector configuration exactly match what your trading partner is expecting. Even a small discrepancy can cause this type of error.

2. Verify that the endpoint URL in your connector configuration is correct and complete. Make sure there are no typos or extra characters.

3. Confirm with your trading partner that they have correctly configured their AS2 server to accept messages from your AS2 identifier at the specified endpoint.

4. If you're using a Network Load Balancer (NLB) or Application Load Balancer (ALB) to terminate TLS, ensure that it's properly configured to forward requests to the Transfer Family AS2 endpoint.

5. Check your CloudWatch logs for any additional error messages or details that might provide more insight into the issue.

6. Verify that your AS2 connector's properties are correctly set by using the AWS CLI command: aws transfer describe-connector --connector-id your-connector-id

If after checking all these points the issue persists, it would be advisable to open a support case with AWS Support. They can investigate the specific configuration of your Transfer Family setup and help identify any potential issues with how the service is sending to the Amazon-hosted AS2 server URL.
Sources
Sending and receiving AS2 messages - AWS Transfer Family
TLS Handshake error on sending even though partner can send with no problem in AS2 | AWS re:Post