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    Server Load Balancer:ModifyCapacityReservation

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    Server Load Balancer:ModifyCapacityReservation

    Last Updated:Sep 28, 2026

    Creates or modifies a capacity reservation.

    Operation description

    ModifyCapacityReservation is an asynchronous operation. The system returns a request ID, but the capacity reservation is not yet complete and the reservation task continues to run in the background. You can call DescribeCapacityReservation to query the status of the capacity reservation:

    • Pending: The capacity reservation is in progress.

    • Provisioned: The capacity reservation is complete.

    • Rebalancing: The capacity reservation is being redistributed 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 instance ID of the Application Load Balancing instance. Before you configure a capacity reservation, the instance must have at least one listener in the Running state.

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    ResetCapacityReservation

    boolean

    No

    Specifies whether to cancel the capacity reservation. Valid values:

    • true: Cancels the capacity reservation.

    • false (default): Does not cancel the capacity reservation. You do not need to specify this parameter when you create or modify a capacity reservation.

    false
    MinimumLoadBalancerCapacity

    object

    No

    The minimum reserved load balancing capacity.

    CapacityUnits

    integer

    No

    The number of LCUs reserved per hour.

    100
    DryRun

    boolean

    No

    Specifies whether to perform a dry run. Valid values:

    • true: Sends a dry run request without reserving resources. The system checks required parameters, request format, and service limits. If the check fails, the corresponding error is returned. If the check succeeds, the DryRunOperation error code is returned.

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

    Valid values:

    • true :

      true

    • false :

      false

    false
    ClientToken

    string

    No

    The client token that is used to ensure the idempotence of the request. You can use the client to generate the token, but you must 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 you do not specify this parameter, the system uses the RequestId of the API request as the ClientToken. The RequestId may be different for each API request.

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    Response elements

    Element

    Type

    Description

    Example

    object

    Schema of 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. No running listeners are found for the ALB instance.
    400 OperationDenied.CapacityReservationNotSupport Resource reservation is not supported. LCU reservation is not supported.
    400 OperationDenied.CapacityUnitsBelowMinimum The operation is not allowed because of CapacityUnitsBelowMinimum. The specified number of LCUs is below the minimum requirement.
    400 OperationDenied.CapacityDecreaseRequestLimitExceeded The operation is not allowed because of CapacityDecreaseRequestLimitExceeded. The limit for decreasing or canceling this reservation has been exceeded.
    400 OperationDenied.PriorRequestNotComplete The operation is not allowed because of PriorRequestNotComplete. The last resource reservation request was not completed
    400 OperationDenied.DeploymentSetExists The operation is not allowed because of OperationDenied.DeploymentSetExists. LCU reservations associated with deployment sets cannot be modified.
    400 OperationDenied.DeploymentSetIsEmpty The operation is not allowed because of OperationDenied.DeploymentSetIsEmpty. The deployment set contains no ECS instances.
    400 OperationDenied.DeploymentSetsConflicts The operation is not allowed because of OperationDenied.DeploymentSetsConflicts. The zones of the ECS instances in the deployment set conflict with the zones of the ALB instance.
    400 OperationDenied.DeploymentSetsNotSupport The operation is not allowed because of OperationDenied.DeploymentSetsNotSupport. Deployment sets are not supported.
    400 OperationDenied.DeploymentSetsStrategyNotMatch The operation is not allowed because of DeploymentSetsStrategyNotMatch. Deployment sets using strategies other than the low latency strategy are not supported.
    400 QuotaExceeded.ReservationMaxLcuPerLb The quota of %s is exceeded, usage %s/%s. Quota for %s has been exceeded. Usage: %s/%s.
    400 QuotaExceeded.ReservationMaxLcuPerRegion The quota of %s is exceeded, usage %s/%s. Quota for %s has been exceeded. Usage: %s/%s.
    400 QuotaExceeded.DeploymentSetsNum The quota of %s is exceeded, usage %s/%s. Quota for %s has been 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.