The error message 'elasticache was unable to validate the authenticated user' indicates that the user credentials provided for accessing the ElastiCache service are invalid or not authorized. It means that the authentication process has failed, and ElastiCache is unable to verify the user's identity.
This error can occur due to several reasons, such as incorrect access key and secret key, expired AWS security token, incorrect IAM permissions, or incorrect endpoint settings. Additionally, this error may also occur if there is an issue with the network connectivity between your client and the ElastiCache cluster.
To resolve this error, you should first ensure that the access key and secret key used for authentication are correct. You can create a new set of access keys from your AWS account page and use them instead of the old ones. If the issue persists, check if the AWS security token has expired and generate a new one if necessary.
Next, verify that the IAM user associated with the access keys has the necessary permissions to access the ElastiCache cluster. Ensure that the IAM policy attached to the user includes the required permissions for accessing the ElastiCache service.
If the above steps do not work, check if the endpoint settings for the ElastiCache cluster are correct. Make sure that the endpoint URL and port number are correct and accessible from your client machine. Finally, check if there are any network connectivity issues between your client and the ElastiCache cluster, and troubleshoot accordingly.