# StartProjectVersion
**Note**
This operation applies only to Amazon Rekognition Custom Labels.
Starts the running of the version of a model. Starting a model takes a while to complete. To check the current state of the model, use [DescribeProjectVersions](API_DescribeProjectVersions.md).
Once the model is running, you can detect custom labels in new images by calling [DetectCustomLabels](API_DetectCustomLabels.md).
**Note**
You are charged for the amount of time that the model is running. To stop a running model, call [StopProjectVersion](API_StopProjectVersion.md).
For more information, see [Running a trained Amazon Rekognition Custom Labels model](https://docs.aws.amazon.com/rekognition/latest/customlabels-dg/running-model.html).
This operation requires permissions to perform the `rekognition:StartProjectVersion` action.
## Request Syntax
```
{
"MaxInferenceUnits": number,
"MinInferenceUnits": number,
"ProjectVersionArn": "string"
}
```
## Request Parameters
For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).
The request accepts the following data in JSON format.
** [MaxInferenceUnits](#API_StartProjectVersion_RequestSyntax) **
The maximum number of inference units to use for auto-scaling the model. If you don't specify a value, Amazon Rekognition Custom Labels doesn't auto-scale the model.
Type: Integer
Valid Range: Minimum value of 1.
Required: No
** [MinInferenceUnits](#API_StartProjectVersion_RequestSyntax) **
The minimum number of inference units to use. A single inference unit represents 1 hour of processing.
For information about the number of transactions per second (TPS) that an inference unit can support, see [Running a trained Amazon Rekognition Custom Labels model](https://docs.aws.amazon.com/rekognition/latest/customlabels-dg/running-model.html).
Use a higher number to increase the TPS throughput of your model. You are charged for the number of inference units that you use.
Type: Integer
Valid Range: Minimum value of 1.
Required: Yes
** [ProjectVersionArn](#API_StartProjectVersion_RequestSyntax) **
The Amazon Resource Name(ARN) of the model version that you want to start.
Type: String
Length Constraints: Minimum length of 20. Maximum length of 2048.
Pattern: `(^arn:[a-z\d-]+:rekognition:[a-z\d-]+:\d{12}:project\/[a-zA-Z0-9_.\-]{1,255}\/version\/[a-zA-Z0-9_.\-]{1,255}\/[0-9]+$)`
Required: Yes
## Response Syntax
```
{
"Status": "string"
}
```
## Response Elements
If the action is successful, the service sends back an HTTP 200 response.
The following data is returned in JSON format by the service.
** [Status](#API_StartProjectVersion_ResponseSyntax) **
The current running status of the model.
Type: String
Valid Values: `TRAINING_IN_PROGRESS | TRAINING_COMPLETED | TRAINING_FAILED | STARTING | RUNNING | FAILED | STOPPING | STOPPED | DELETING | COPYING_IN_PROGRESS | COPYING_COMPLETED | COPYING_FAILED | DEPRECATED | EXPIRED`
## Errors
For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).
** AccessDeniedException **
You are not authorized to perform the action.
HTTP Status Code: 400
** InternalServerError **
Amazon Rekognition experienced a service issue. Try your call again.
HTTP Status Code: 500
** InvalidParameterException **
Input parameter violated a constraint. Validate your parameter before calling the API operation again.
HTTP Status Code: 400
** LimitExceededException **
An Amazon Rekognition service limit was exceeded. For example, if you start too many jobs concurrently, subsequent calls to start operations (ex: `StartLabelDetection`) will raise a `LimitExceededException` exception (HTTP status code: 400) until the number of concurrently running jobs is below the Amazon Rekognition service limit.
HTTP Status Code: 400
** ProvisionedThroughputExceededException **
The number of requests exceeded your throughput limit. If you want to increase this limit, contact Amazon Rekognition.
HTTP Status Code: 400
** ResourceInUseException **
The specified resource is already being used.
HTTP Status Code: 400
** ResourceNotFoundException **
The resource specified in the request cannot be found.
HTTP Status Code: 400
** ThrottlingException **
Amazon Rekognition is temporarily unable to process the request. Try your call again.
HTTP Status Code: 500
## 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/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/rekognition-2016-06-27/StartProjectVersion)
+ [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/rekognition-2016-06-27/StartProjectVersion)