MongoDB Documentation, Release 3.0.4 Preparedness Procedures Follow the downgrade procedures: • Remove or downgrade version 2 text indexes (page 874) before downgrading MongoDB 2.6 to 2.4. • Remove or downgrade version 2 2dsphere indexes (page 875) before downgrading MongoDB 2.6 to 2.4. • Downgrade 2.6 User Authorization Model (page 872). If you have upgraded to the 2.6 user authorization model, you must downgrade the user model to 2.4 before downgrading MongoDB 2.6 to 2.4. • To downgrade sharded clusters, see Downgrade a 2.6 Sharded Cluster (page 876). • To downgrade replica sets, see Downgrade a 2.6 Replica Set (page 875). • To downgrade a standalone MongoDB instance, see Downgrade 2.6 Standalone mongod Instance (page 875). • For a replica set, it is only necessary to run the downgrade process on the primary as the changes will automati- cally replicate to the secondaries. • For sharded clusters, although the procedure lists the downgrade of the cluster’s authorization data first, you may downgrade the authorization data of the cluster or shards first. • You must have the admin.system.backup_users and admin.system.new_users collections cre- ated during the upgrade process. • Important . The downgrade process returns the user data to its state prior to upgrading to 2.6 authorization model. Any changes made to the user/role data using the 2.6 users model will be lost. Access Control Prerequisites To downgrade the authorization model, you must connect as a user with the following privileges : If no user exists with the appropriate privileges , create an authorization model downgrade user: Step 1: Connect as user with privileges to manage users and roles. Connect and authenticate as a user with userAdminAnyDatabase (page 412). Step 2: Create a role with required privileges. Using the db.createRole method, create a role (page 325) with the required privileges. { resource: { db: "admin", collection: "system.new_users" }, actions: [ "find", "insert", { resource: { db: "admin", collection: "system.backup_users" }, actions: [ "find" ] } { resource: { db: "admin", collection: "system.users" }, actions: [ "find", "remove", "insert"] } { resource: { db: "admin", collection: "system.version" }, actions: [ "find", "update" ] } use admin db.createRole( { role: "downgradeAuthRole", privileges: [ { resource: { db: "admin", collection: "system.new_users" }, actions: [ "find", "insert" Chapter 12. Release Notes 872 Downgrade 2.6 User Authorization Model If you have upgraded to the 2.6 user authorization model, you must first downgrade the user authorization model to 2.4 before before downgrading MongoDB 2.6 to 2.4. Considerations