How to reproduce PartitionSelectorException?

[KimTaehee]

Questions

First, I appreciate you keeping Lettuce active.
I faced PartitionSelectorException during manual CLUSTER FAILOVER on my production environment. So I tried to reproduce the exception but failed.
Any feedback or ideas would be very helpful.

My questions are:

1. Is there a scenario where PartitionSelectorException might occur when running the CLUSTER FAILOVER command manually? I guess it is, but I couldn't find it.
2. As far as I understand, I don't expect to get a PartitionSelectorException if the cluster is stable and Lettuce has refreshed the topology periodically or adaptively. If so, is there a possible way to catch and retry it? (e.g.: blocks adaptive refresh and retries the command after that)

Environment

• Lettuce version(s): 5.2.2.RELEASE
• Redis version: 3.2.12 cluster mode

What I already checked:

1. Cannot determine a partition for slot #2252 (comment)
2. https://groups.google.com/g/lettuce-redis-client-users/c/AFF00Ch6x0s/m/Y6AySSWRAgAJ
3. PartitionSelectorException during refresh of Partitions #2178 // Only for 6.2.0.RELEASE

[mp911de]

PartitionSelectorException happens if there is no read or write node for a hash slot. That is, if there is no master currently serving a slot or, if the selection wants to send a command towards a replica, that there is no replica available for the slot.

You can reproduce the exception by configuring a cluster that doesn't cover all hash slots and then issuing a command against a hash slot that has no master for it.