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The leader may be unable to fence out producers during a rebalance if, for example, it is unable to reach or locate a transaction coordinator.

Automatically failing marking all tasks for that connector as failed may seem appealing at first, but the user’s first instincts in this situation are likely to be to restart those tasks, which could cause them to come up without zombies from a prior generation being fenced out firstit's unclear how to do this in a reasonable way that doesn't mask the fact that there are actually tasks still running for that connector (which there very well may be).

Marking the entire rebalance as failed and forcing a follow-up round would be simpler to design and less likely to lead to compromised delivery guarantees, but it would also impact any other connectors and tasks that were due to be reassigned in that round.

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