Dialogflow operations call throws ValidationException

[HarinJoshi25]

This is the file i am running on my local to train my agent through php client library.
Following is the code that i am running on my local server:

<?php

require 'vendor/autoload.php';
use Google\Cloud\Dialogflow\V2\SessionsClient;
use Google\Cloud\Dialogflow\V2\AgentsClient;

function get_agent($projectId,$sessionId){

$test = array('credentials' => 'client-secret.json');
    $sessionsClient = new SessionsClient($test);
    $session = $sessionsClient->sessionName($projectId, $sessionId ?: uniqid());
    printf('Session path: %s' . PHP_EOL, $session);

$agentsClient = new AgentsClient();
try {
    $formattedParent = $agentsClient->projectName($projectId);
    $operationResponse = $agentsClient->trainAgent($formattedParent);
    $operationResponse->pollUntilComplete();
    if ($operationResponse->operationSucceeded()) {
        // operation succeeded and returns no value
        print("training successful!");
    } else {
        $error = $operationResponse->getError();
        handleError($error);
        print($error);
    }
    }
    finally {
    $agentsClient->close();
    }
}
get_agent('<<myprojectid>>','12346');

Here myprojectid is the project id of my agent on dialogflow which i am providing as an input.
following is the error that i am getting when i run this script:

PHP Fatal error: Uncaught Google\ApiCore\ValidationException: Failed to build request, as the provided path (google.longrunning.Operations/GetOperation) was not found in the configuration. in /home/mandar/composer/vendor/google/gax/src/RequestBuilder.php:80
Stack trace:
#0 /home/mandar/composer/vendor/google/gax/src/Transport/RestTransport.php(109): Google\ApiCore\RequestBuilder->build('google.longrunn...', Object(Google\LongRunning\GetOperationRequest), Array)
#1 /home/mandar/composer/vendor/google/gax/src/GapicClientTrait.php(479): Google\ApiCore\Transport\RestTransport->startUnaryCall(Object(Google\ApiCore\Call), Array)
#2 /home/mandar/composer/vendor/google/gax/src/Middleware/CredentialsWrapperMiddleware.php(61): Google\ApiCore\LongRunning\Gapic\OperationsGapicClient->Google\ApiCore{closure}(Object(Google\ApiCore\Call), Array)
#3 /home/mandar/composer/vendor/google/gax/src/Middleware/FixedHeaderMiddleware.php(67): Google\ApiCore\Middleware\CredentialsWrapperMiddleware->__invoke(Object(Google\ApiCore\Call), Array)
#4 /hom in /home/mandar/composer/vendor/google/gax/src/RequestBuilder.php on line 80

[dwsupplee]

Thanks for the report @HarinJoshi25, we're taking a look.

[dwsupplee]

It looks like the repository which hosts the configurations for building out our generated clients has an issue with information required for our REST based transport. We've gone ahead and opened a change to get this fixed internally - in the meantime you should be able to work around this by enabling the gRPC extension. I'll ping back here when the fix lands. Thanks again for the report!

[dwsupplee]

@HarinJoshi25 a fix for this just landed in: #2102