# FailoverDBCluster
<a name="API_FailoverDBCluster"></a>

Forces a failover for a cluster.

A failover for a cluster promotes one of the Amazon DocumentDB replicas (read-only instances) in the cluster to be the primary instance (the cluster writer).

If the primary instance fails, Amazon DocumentDB automatically fails over to an Amazon DocumentDB replica, if one exists. You can force a failover when you want to simulate a failure of a primary instance for testing.

## Request Parameters
<a name="API_FailoverDBCluster_RequestParameters"></a>

 For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).

 ** DBClusterIdentifier **   
A cluster identifier to force a failover for. This parameter is not case sensitive.  
Constraints:  
+ Must match the identifier of an existing `DBCluster`.
Type: String  
Required: No

 ** TargetDBInstanceIdentifier **   
The name of the instance to promote to the primary instance.  
You must specify the instance identifier for an Amazon DocumentDB replica in the cluster. For example, `mydbcluster-replica1`.  
Type: String  
Required: No

## Response Elements
<a name="API_FailoverDBCluster_ResponseElements"></a>

The following element is returned by the service.

 ** DBCluster **   
Detailed information about a cluster.   
Type: [DBCluster](API_DBCluster.md) object

## Errors
<a name="API_FailoverDBCluster_Errors"></a>

For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).

 ** DBClusterNotFoundFault **   
 `DBClusterIdentifier` doesn't refer to an existing cluster.   
HTTP Status Code: 404

 ** InvalidDBClusterStateFault **   
The cluster isn't in a valid state.  
HTTP Status Code: 400

 ** InvalidDBInstanceState **   
 The specified instance isn't in the *available* state.   
HTTP Status Code: 400

## See Also
<a name="API_FailoverDBCluster_SeeAlso"></a>

For more information about using this API in one of the language-specific Amazon SDKs, see the following:
+  [Amazon Command Line Interface V2](https://docs.amazonaws.cn/goto/cli2/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for .NET V4](https://docs.amazonaws.cn/goto/DotNetSDKV4/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for C\+\+](https://docs.amazonaws.cn/goto/SdkForCpp/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for Go v2](https://docs.amazonaws.cn/goto/SdkForGoV2/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for Java V2](https://docs.amazonaws.cn/goto/SdkForJavaV2/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for JavaScript V3](https://docs.amazonaws.cn/goto/SdkForJavaScriptV3/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for Kotlin](https://docs.amazonaws.cn/goto/SdkForKotlin/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for PHP V3](https://docs.amazonaws.cn/goto/SdkForPHPV3/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for Python](https://docs.amazonaws.cn/goto/boto3/docdb-2014-10-31/FailoverDBCluster) 
+  [Amazon SDK for Ruby V3](https://docs.amazonaws.cn/goto/SdkForRubyV3/docdb-2014-10-31/FailoverDBCluster)