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Server Load Balancer:ModifyCapacityReservation

Last Updated:May 29, 2026

Creates and updates a Load Balancer Capacity Unit (LCU) reservation.

Operation description

ModifyCapacityReservation is an asynchronous operation. After you send a request, the system returns a request ID and runs the task in the background. The LCU reservation is not immediately updated. You can call the DescribeCapacityReservation operation to query the status of an LCU reservation:

  • If an LCU reservation is in the Pending state, it is being created.

  • If an LCU reservation is in the Provisioned state, it is created.

  • If an LCU reservation is in the Rebalancing state, it is being rebalanced across zones.

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RAM authorization

No authorization for this operation. If you encounter issues with this operation, contact technical support.

Request syntax

POST  HTTP/1.1

Request parameters

Parameter

Type

Required

Description

Example

LoadBalancerId

string

Yes

The ID of the Application Load Balancer (ALB) instance.

alb-iv9gj3spak6fbj****

ResetCapacityReservation

boolean

No

Specifies whether to cancel the LCU reservation. Valid values:

  • true: Cancels the LCU reservation.

  • false (default): Does not cancel the LCU reservation. You do not need to specify this parameter when creating or updating an LCU reservation.

false

MinimumLoadBalancerCapacity

object

No

The minimum LCU value to reserve.

CapacityUnits

integer

No

The number of LCUs to reserve per hour.

100

DryRun

boolean

No

Specifies whether to perform a dry run. Valid values:

  • true: Sends a check request but does not reserve any resources. The system checks the request for required parameters, format, and service limits. If the check fails, an error is returned. If the check passes, the DryRunOperation error code is returned.

  • false (default): Sends a normal request. After the request passes the check, an HTTP 2xx status code is returned and the operation is performed.

Valid values:

  • true :

    true

  • false :

    false

false

ClientToken

string

No

A client token to ensure the idempotence of the request. Generate a token from your client and make sure that the token is unique among different requests. The token can contain only ASCII characters and cannot exceed 64 characters in length.

Note

If this parameter is not specified, the system uses the RequestId as the ClientToken. The RequestId of each API request is different.

5A2CFF0E-5718-45B5-9D4D-70B3FF3898

Response elements

Element

Type

Description

Example

object

The schema of the response.

RequestId

string

The request ID.

593B0448-D13E-4C56-AC0D-FDF0F******

Examples

Success response

JSON format

{
  "RequestId": "593B0448-D13E-4C56-AC0D-FDF0F******"
}

Error codes

HTTP status code

Error code

Error message

Description

400 OperationDenied.ListenerNotFound The operation is not allowed because of ListenerNotFound.
400 OperationDenied.CapacityReservationNotSupport Resource reservation is not supported.
400 OperationDenied.CapacityUnitsBelowMinimum The operation is not allowed because of CapacityUnitsBelowMinimum.
400 OperationDenied.CapacityDecreaseRequestLimitExceeded The operation is not allowed because of CapacityDecreaseRequestLimitExceeded.
400 OperationDenied.PriorRequestNotComplete The operation is not allowed because of PriorRequestNotComplete.
400 OperationDenied.DeploymentSetExists The operation is not allowed because of OperationDenied.DeploymentSetExists.
400 OperationDenied.DeploymentSetIsEmpty The operation is not allowed because of OperationDenied.DeploymentSetIsEmpty.
400 OperationDenied.DeploymentSetsConflicts The operation is not allowed because of OperationDenied.DeploymentSetsConflicts.
400 OperationDenied.DeploymentSetsNotSupport The operation is not allowed because of OperationDenied.DeploymentSetsNotSupport.
400 OperationDenied.DeploymentSetsStrategyNotMatch The operation is not allowed because of DeploymentSetsStrategyNotMatch.
400 QuotaExceeded.ReservationMaxLcuPerLb The quota of %s is exceeded, usage %s/%s.
400 QuotaExceeded.ReservationMaxLcuPerRegion The quota of %s is exceeded, usage %s/%s.
400 QuotaExceeded.DeploymentSetsNum The quota of %s is exceeded, usage %s/%s.
400 OperationDenied.DeploymentSetsNotSharedToAlb DeploymentSets are not shared to alb. These deployment sets are not shared to the ALB.
404 ResourceNotFound.LoadBalancer The specified resource of %s is not found. The specified resource of %s is not found.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.