All known issues filed against the 2.0 release are contained within the official CouchDB JIRA instance.
The following are some highlights of known issues for which fixes did not land in time for the 2.0.0 release:
COUCHDB-2980: The replicator (whether invoked via _replicate or a document stored in the _replicator database) understands two kinds of source and target:
Whenever the latter type is used, this refers to a local unclustered database, not a clustered one.
In a future release we hope to support “local” source or target specs to clustered databases. For now, we recommend always using the URL format for both source and target specifications.
COUCHDB-3034: CouchDB will occasionally return 500 errors when multiple clients attempt to PUT or DELETE the same database concurrently.
COUCHDB-3119: Adding nodes to a cluster fails if the Erlang node name is not couchdb (of the form couchdb@hostname.)
COUCHDB-3050: Occasionally the dev/run script used for development purposes to start a local 3-node cluster will fail to start one or more nodes.
COUCHDB-2817: The compaction daemon will only compact views for shards that contain the design document.
COUCHDB-2804: The fast_view optimization is not enabled on the clustered interface.