Upgrade a Standalone to 4.0

Upgrade Version Path

To upgrade an existing MongoDB deployment to 4.0, you must be running a 3.6-series release.

To upgrade from a version earlier than the 3.6-series, you must successively upgrade major releases until you have upgraded to 3.6-series. For example, if you are running a 3.4-series, you must upgrade first to 3.6 before you can upgrade to 4.0.

Check Driver Compatibility

Before you upgrade MongoDB, check that you're using a MongoDB 4.0-compatible driver. Consult the driver documentation for your specific driver to verify compatibility with MongoDB 4.0.

Upgraded deployments that run on incompatible drivers might encounter unexpected or undefined behavior.

Preparedness

Before beginning your upgrade, see the Compatibility Changes in MongoDB 4.0 document to ensure that your applications and deployments are compatible with MongoDB 4.0. Resolve the incompatibilities in your deployment before starting the upgrade.

Before upgrading MongoDB, always test your application in a staging environment before deploying the upgrade to your production environment.

Downgrade Consideration

Starting in MongoDB 7.0, you cannot downgrade your deployment's binary version without assistance from support.

To learn more, see Downgrade 7.0 to 6.0.

Remove Support for MONGODB-CR

Starting in version 4.0, MongoDB removes support for the deprecated MongoDB Challenge-Response (MONGODB-CR) authentication mechanism.

If your deployment has user credentials stored in MONGODB-CR schema, you must upgrade to Salted Challenge Response Authentication Mechanism (SCRAM) before you upgrade to version 4.0. For information on upgrading to SCRAM, see Upgrade to SCRAM.

Remove Support for $isolated

MongoDB drops support for the $isolated operator. If you have an existing partial index that includes the $isolated operator or a view that includes a $isolated operator, recreate the index or view without the operator in the definition before upgrading.

Feature Compatibility Version

The 3.6 instance must have featureCompatibilityVersion set to 3.6. To check featureCompatibilityVersion:

db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )

The operation should return a result that includes "featureCompatibilityVersion" : { "version" : "3.6" }.

To set or update featureCompatibilityVersion, run the following command:

db.adminCommand( { setFeatureCompatibilityVersion: "3.6" } )

For more information, see setFeatureCompatibilityVersion.

Via Package Manager

If you installed MongoDB from the MongoDB apt, yum, dnf, or zypper repositories, you should upgrade to 4.0 using your package manager.

Follow the appropriate 4.0 installation instructions for your Linux system. This will involve adding a repository for the new release, then performing the actual upgrade process.

Manually

If you have not installed MongoDB using a package manager, you can manually download the MongoDB binaries from the MongoDB Download Center.

See 4.0 installation instructions for more information.