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Upgrade to SCRAM

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  • Considerations
  • Prerequisites
  • Upgrade 2.6 MONGODB-CR User Credentials to SCRAM User Credentials
  • Result


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

If you have user credentials stored in MONGODB-CR, you must upgrade to Salted Challenge Response Authentication Mechanism (SCRAM) before you upgrade to version 4.0.

The command listed in this procedure is only available in MongoDB 3.0 through MongoDB 3.6.

The procedure to upgrade to SCRAM discards the MONGODB-CR credentials used by 2.6. As such, the procedure is irreversible, short of restoring from backups.

The procedure also disables MONGODB-CR as an authentication mechanism.

To upgrade the authentication model, you must have a user in the admin database with the role userAdminAnyDatabase.

Applicable only if you are upgrading from 2.6 to 3.0

  • Once you upgrade the MongoDB binaries to version 3.0, allow your MongoDB deployment to run for a day or two before following this procedure. This allows 3.0 some time to "burn in" and decreases the likelihood of downgrades occurring after the user privilege model upgrade. The user authentication and access control will continue to work as it did in 2.6.

  • If you decide to upgrade the user authentication model immediately instead of waiting the recommended "burn in" period, then for sharded clusters, you must wait at least 10 seconds after upgrading the sharded clusters to run the authentication upgrade command.

For a replica set, it is only necessary to run the upgrade process on the primary as the changes will automatically replicate to the secondaries.

For a sharded cluster, connect to one mongos instance and run the upgrade procedure to upgrade the cluster's authentication data. By default, the procedure will upgrade the authentication data of the shards as well.

To override this behavior, run authSchemaUpgrade with the upgradeShards: false option. If you choose to override, you must run the upgrade procedure on the mongos first, and then run the procedure on the primary members of each shard.

For a sharded cluster, do not run the upgrade process directly against the config servers. Instead, perform the upgrade process using one mongos instance to interact with the config database.

Once upgraded, you must upgrade all drivers used by applications that will connect to upgraded database instances to version that support SCRAM. The minimum driver versions that support SCRAM are:

Driver Language


Driver Language



See the MongoDB Drivers Page for links to download upgraded drivers.

Before upgrading the authentication model, your binaries must be at least version 3.0.

For sharded clusters, ensure that all cluster components are at least 3.0.

To upgrade, see upgrade MongoDB binaries to 3.0.


The procedure to upgrade to SCRAM discards the MONGODB-CR credentials used by 2.6. As such, the procedure is irreversible, short of restoring from backups.

The procedure also disables MONGODB-CR as an authentication mechanism.


To use SCRAM, a driver upgrade is necessary if your current driver version does not support SCRAM. See required driver versions for details.


Connect and authenticate to the mongod instance for a single deployment, the primary mongod for a replica set, or a mongos for a sharded cluster as an admin database user with the role userAdminAnyDatabase.


Use the authSchemaUpgrade command in the admin database to update the user data using the mongo shell.


The command is available only in MongoDB versions 3.0 through 3.6. Refer to the specific version of the manual for details on on the command.

db.adminCommand({authSchemaUpgrade: 1});

In case of error, you may safely rerun the authSchemaUpgrade command.

For a sharded cluster without shard local users, authSchemaUpgrade will, by default, upgrade the authorization data of the shards as well, completing the upgrade.

You can, however, override this behavior by including upgradeShards: false in the command, as in the following example:

{authSchemaUpgrade: 1, upgradeShards: false }

If you override the default behavior or your cluster has shard local users, after running authSchemaUpgrade on a mongos instance, you will need to connect to the primary for each shard and repeat the upgrade process after upgrading on the mongos.

After this procedure is complete, all users in the database will have SCRAM credentials, and any subsequently-created users will also have this type of credentials.

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