When a mongos/mongod cannot connect to another node due to incompatible wireVersion that is intentional due to featureCompatibilityVersion, we log a generic error message like “remote host has incompatible wire version: IncompatibleServerVersion: Server min and max wire version are incompatible (6,6) with client min wire version (5,5)”. One idea to make this error message more informative is to provide a dochub link to the upgrade/downgrade documentation in case a user encounters it due to failing to upgrade one of their binaries.