From fabric-peer-endorser-committer channel, it is reported that upgrading to CouchDB 2.3 will cause an error:
couchdb has changed the data type in response for `CreateDatabaseIfNotExist()` check from purge_seq of int to string, while couchdb client expects int. This is a bug opened against CouchDB: https://github.com/apache/couchdb/issues/1809.
Fabric will need to make a code change to tolerate the CouchDB change. Since Fabric doesn't use purge_seq or update_seq (which have changed in couchdb 2.3), Fabric will make a change to simply disregard these two fields.