I have a staging mongodb 4.0.19 sharded cluster with 2 replica set shards . I want to remove one shard. I followed the documentation: https://docs.mongodb.com/v4.0/tutorial/remove-shards-from-cluster/index.html and used removeShard command. But one chunk cannot be moved: the config.system.sessions chunk. I have the following error:
2020-07-30T09:21:07.330+0200 W SHARDING [conn21] Chunk move failed :: caused by :: OperationFailed: Data transfer error: migrate failed: InvalidUUID: Cannot create collection config.system.sessions because we already have an identically named collection with UUID b788097c-5ba1-464c-9064-0b7faed5c196, which differs from the donor's UUID 22588e86-20a2-4cdf-a70e-803fbd7b3e5a. Manually drop the collection on this shard if it contains data from a previous incarnation of config.system.sessions
This prevents draining chunks to finish. Is there any way to drop that collection or to force removeShard command to finish ?