Error: kafka.common.AdminCommandFailedException: The reassignment failed due to an unexpected error.

Hi,

The "NO_REASSIGNMENT_IN_PROGRESS" is a result that you may get when there's no reassignment currently in progress for the specified partitions, which might be the case if a previous reassignment completed or failed, or if no reassignment was initiated.

The error message "The reassignment failed due to an unexpected error" is a more generic message and it indicates that something went wrong during the reassignment operation, but doesn't provide specific details about the cause. There are several potential reasons for this error, including issues with the broker, replication factor issues, issues with the ZooKeeper, and so on.

Here are couple of things you could consider:

1. Ensure healthy cluster state: Before doing reassignment, ensure your MSK cluster is in a healthy state. All brokers should be up and running, and underreplicated partitions should ideally be zero.

2. Validate your reassignment JSON: Make sure the JSON file used for partition reassignment is correct and can be parsed successfully. The tool does not validate if the reassignment maintains the replication factor or not, so ensure this is manually validated.

If none of the above helps, it might be useful to provide more details. In that case, please create a support case with us, using the following link:

https://console.aws.amazon.com/support/home#/case/create