AWS SDK Version 3 for .NET
API Reference

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Sends user input (text or speech) to Amazon Lex. Clients use this API to send text and audio requests to Amazon Lex at runtime. Amazon Lex interprets the user input using the machine learning model that it built for the bot.

The PostContent operation supports audio input at 8kHz and 16kHz. You can use 8kHz audio to achieve higher speech recognition accuracy in telephone audio applications.

In response, Amazon Lex returns the next message to convey to the user. Consider the following example messages:

Not all Amazon Lex messages require a response from the user. For example, conclusion statements do not require a response. Some messages require only a yes or no response. In addition to the message, Amazon Lex provides additional context about the message in the response that you can use to enhance client behavior, such as displaying the appropriate client user interface. Consider the following examples:

In addition, Amazon Lex also returns your application-specific sessionAttributes. For more information, see Managing Conversation Context.


For .NET Core and PCL this operation is only available in asynchronous form. Please refer to PostContentAsync.

Namespace: Amazon.Lex
Assembly: AWSSDK.Lex.dll
Version: 3.x.y.z


public virtual PostContentResponse PostContent(
         PostContentRequest request
Type: Amazon.Lex.Model.PostContentRequest

Container for the necessary parameters to execute the PostContent service method.

Return Value
The response from the PostContent service method, as returned by Lex.


BadGatewayException Either the Amazon Lex bot is still building, or one of the dependent services (Amazon Polly, AWS Lambda) failed with an internal service error.
BadRequestException Request validation failed, there is no usable message in the context, or the bot build failed, is still in progress, or contains unbuilt changes.
ConflictException Two clients are using the same AWS account, Amazon Lex bot, and user ID.
DependencyFailedException One of the dependencies, such as AWS Lambda or Amazon Polly, threw an exception. For example, If Amazon Lex does not have sufficient permissions to call a Lambda function. If a Lambda function takes longer than 30 seconds to execute. If a fulfillment Lambda function returns a Delegate dialog action without removing any slot values.
InternalFailureException Internal service error. Retry the call.
LimitExceededException Exceeded a limit.
LoopDetectedException This exception is not used.
NotAcceptableException The accept header in the request does not have a valid value.
NotFoundException The resource (such as the Amazon Lex bot or an alias) that is referred to is not found.
RequestTimeoutException The input speech is too long.
UnsupportedMediaTypeException The Content-Type header (PostContent API) has an invalid value.

Version Information

.NET Framework:
Supported in: 4.5, 4.0, 3.5

Portable Class Library:
Supported in: Windows Store Apps
Supported in: Windows Phone 8.1
Supported in: Xamarin Android
Supported in: Xamarin iOS (Unified)
Supported in: Xamarin.Forms

See Also