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New in version 3.2.



Terminates an operation as specified by the operation ID. The mongo shell provides the db.killOp() helper. To find operations and their corresponding IDs, see $currentOp or db.currentOp().

The killOp command must be run against the admin database.

To run killOp, use the db.runCommand( { <command> } ) method.

The command has the following form:

{ "killOp": 1, "op": <opid>, comment: <any> }
Parameter Type Description
op number An operation ID.
comment any

Optional. A user-provided comment to attach to this command. Once set, this comment appears alongside records of this command in the following locations:

A comment can be any valid BSON type (string, integer, object, array, etc).

New in version 4.4.


Terminate running operations with extreme caution. Only use killOp to terminate operations initiated by clients and do not terminate internal database operations.


Do not use killOp to terminate an in-progress index builds in replica sets or sharded clusters. Use dropIndexes on the primary to drop the index. See Abort In-Progress Index Builds.

Access Control

On systems running with authorization, to kill operations not owned by the user, the user must have access that includes the killop privilege action.

Changed in version 3.2.9: On mongod instances, users can kill their own operations even without the killop privilege action.

Sharded Cluster

Starting in MongoDB 4.0, the killOp command can be run on a mongos and can kill queries (i.e. read operations) that span shards in a cluster. The killOp command from the mongos does not propagate to the shards when the operation to be killed is a write operation.

For information on how to list sharding operations that are active on a mongos, see the localOps parameter in $currentOp.

For more information and examples on killing operations on a sharded cluster, see:


The following example uses killOp to target the running operation with opid 3478.

db.adminCommand( { "killOp": 1, "op": 3478 } )

The operation returns the following result:

{ "info" : "attempting to kill op", "ok" : 1 }

killOp reports success if it succeeded in marking the specified operation for termination. Operations may not actually be terminated until they reach an appropriate interruption point. Use $currentOp or db.currentOp() to confirm the target operation was terminated.