# CreateSession
Creates a new session context within a workflow run to manage conversation state and acts.
## Request Syntax
```
PUT /workflow-definitions/workflowDefinitionName/workflow-runs/workflowRunId/sessions HTTP/1.1
Content-type: application/json
{
"clientToken": "string"
}
```
## URI Request Parameters
The request uses the following URI parameters.
** [workflowDefinitionName](#API_CreateSession_RequestSyntax) **
The name of the workflow definition containing the workflow run.
Length Constraints: Minimum length of 1. Maximum length of 40.
Pattern: `[a-zA-Z0-9_-]{1,40}`
Required: Yes
** [workflowRunId](#API_CreateSession_RequestSyntax) **
The unique identifier of the workflow run to create the session in.
Pattern: `[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}`
Required: Yes
## Request Body
The request accepts the following data in JSON format.
** [clientToken](#API_CreateSession_RequestSyntax) **
A unique, case-sensitive identifier that you provide to ensure the idempotency of the request.
Type: String
Length Constraints: Minimum length of 33. Maximum length of 256.
Pattern: `[a-zA-Z0-9](-*[a-zA-Z0-9]){0,256}`
Required: No
## Response Syntax
```
HTTP/1.1 201
Content-type: application/json
{
"sessionId": "string"
}
```
## Response Elements
If the action is successful, the service sends back an HTTP 201 response.
The following data is returned in JSON format by the service.
** [sessionId](#API_CreateSession_ResponseSyntax) **
The unique identifier for the created session.
Type: String
Pattern: `[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}`
## Errors
For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).
[AccessDeniedException](API_AccessDeniedException.md)
You don't have sufficient permissions to perform this action.
** message **
You don't have sufficient permissions to perform this action. Verify your IAM permissions and try again.
HTTP Status Code: 403
[ConflictException](API_ConflictException.md)
The request could not be completed due to a conflict with the current state of the resource.
** message **
The requested operation conflicts with the current state of the resource.
** resourceId **
The identifier of the resource that caused the conflict.
** resourceType **
The type of resource that caused the conflict.
HTTP Status Code: 409
[InternalServerException](API_InternalServerException.md)
An internal server error occurred. Please try again later.
** message **
The service encountered an internal error. Try again later.
** reason **
The reason for the internal server error.
** retryAfterSeconds **
The number of seconds to wait before retrying the request.
HTTP Status Code: 500
[ResourceNotFoundException](API_ResourceNotFoundException.md)
The requested resource was not found.
** message **
The specified resource was not found.
** resourceId **
The identifier of the resource that wasn't found.
** resourceType **
The type of resource that wasn't found.
HTTP Status Code: 404
[ServiceQuotaExceededException](API_ServiceQuotaExceededException.md)
The request would exceed a service quota limit.
** message **
The request would exceed one or more service quotas for your account.
** quotaCode **
The code for the specific quota that was exceeded.
** resourceId **
The identifier of the resource that exceeded the quota.
** resourceType **
The type of resource that exceeded the quota.
** serviceCode **
The service code for the quota that was exceeded.
HTTP Status Code: 402
[ThrottlingException](API_ThrottlingException.md)
The request was throttled due to too many requests. Please try again later.
** message **
The request was denied due to request throttling.
** quotaCode **
The quota code related to the throttling.
** retryAfterSeconds **
The number of seconds to wait before retrying the throttled request.
** serviceCode **
The service code where throttling occurred.
HTTP Status Code: 429
[ValidationException](API_ValidationException.md)
The input parameters for the request are invalid.
** fieldList **
The list of fields that failed validation.
** message **
The input fails to satisfy the constraints specified by the service.
** reason **
The reason for the validation failure.
HTTP Status Code: 400
## See Also
For more information about using this API in one of the language-specific AWS SDKs, see the following:
+ [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/nova-act-2025-08-22/CreateSession)
+ [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/nova-act-2025-08-22/CreateSession)