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Revision as of 19:40, 3 June 2016 by imported>Eevans (external links to driver documentation)
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Node.js driver and native protocol versions

In the absence of an explicitly configured maxVersion, the Node.js driver will use a constant as the default. As the driver works through the contact points at startup, it will attempt to use this default, and failing that, decrement and try again. Once it has established the first successful connection, this negotiated protocol version is used for all subsequent connections, and any node that does not support it is skipped entirely. This can result in severe imbalances of client connections during an upgrade where the default native protocol version is higher than the version being upgraded.

When upgrading, be aware of any changes to the default native protocol version, and ensure that protocolOptions.maxVersion is explicitly configured for the least common denominator node until such time as the upgrade is complete.

See also: Mixed cluster versions and rolling upgrades