How to Fix the Google Actions OAuth Setup Error "Reached Limit on Number of Clients"

Struggling to Register Devices with Google Assistant API? Here's What You Need to Know

If you've ever tried to set up the Google Assistant API on a new device, you know how challenging it can be to navigate Google Cloud and Google Actions. For some developers, like yourself, an unexpected roadblock can appear: an error saying "Reached limit on number of clients in this project." 😣

This issue can be particularly confusing if your Google Cloud Project is brand new, with no prior client credentials registered. Imagine going through the process of setting up multiple projects and even switching Google accounts, only to end up with the same result each time. It's enough to make anyone wonder if there's a hidden restriction somewhere in the system!

With limited resources available online about this error, many developers find themselves stuck, unsure whether the problem lies with the API, the project, or the account itself. I've been there too, experimenting and troubleshooting, looking for a solution that finally gets those credentials in place.

But don't worry – while this issue is frustrating, there are some tips and workarounds that can help you move forward with your setup. Let's explore why this error happens and what you can do to get your OAuth credentials downloaded successfully. 🔧

Solving OAuth Credential Errors in Google Actions for Device Registration

The Python backend script is specifically designed to create OAuth 2.0 client credentials on Google Cloud, which is essential when you’re working with the Google Assistant API to register devices. One of the most crucial parts of the script is retrieving the default Google Cloud credentials with google.auth.default(). This ensures that the correct permissions are granted without needing to hardcode sensitive details, which both enhances security and simplifies credential management. Once we have the credentials, credentials.refresh(Request()) is used to renew the token, guaranteeing it’s valid before making API calls. This is particularly useful for long-running applications, where token expiry could disrupt processes. Imagine this as keeping your "key" fresh while interacting with a secure system.

With the credentials in place, the script sends a POST request to the https://oauth2.googleapis.com endpoint, dynamically structured using the project ID to ensure flexibility across multiple projects. The payload includes essential details like client_name and redirect URIs, which specify how Google should handle your app’s redirection after successful authentication. If you’ve ever struggled to set up a device for an API that keeps redirecting to login screens, you’ll appreciate how critical this part is. Once the request is sent, the script checks the response. If successful, it returns the OAuth client details; otherwise, it logs the error for further analysis.

The JavaScript frontend solution also aims to create an OAuth client but does so directly from the client side, making it more accessible for web-based applications. Using gapi.client.init() initializes the Google API client with a specific API key, and once the client library is loaded, gapi.client.oauth2.projects.oauthClients.create() attempts to create a new OAuth client. This command is especially helpful if you’re developing for the web and prefer handling user authentication directly in the browser. However, it’s crucial to handle errors effectively, as users could easily encounter rate limits or permission issues when testing client creation.

For testing and validation, Python’s unittest library plays a significant role in confirming that each function works as expected. The assertions like assertIsNotNone and assertIn confirm that the correct responses are returned, minimizing the chance of hidden errors later. Unit tests not only verify successful OAuth client creation but also help identify specific error states, such as the infamous “reached limit” error. This structured approach, combined with detailed error handling, significantly improves reliability and helps developers like you avoid repeat issues. So, whether you’re managing Google Cloud projects for a personal device setup or a large-scale deployment, these scripts and methods can streamline the process, making device registration with Google Assistant a smoother experience. 🔧

# Import necessary libraries for Google Cloud and HTTP requests
import google.auth
from google.auth.transport.requests import Request
import requests
import json
# Define function to create new OAuth 2.0 client
def create_oauth_client(project_id, client_name):
    # Get credentials for Google Cloud API
    credentials, project = google.auth.default()
    credentials.refresh(Request())
    # Define endpoint for creating OAuth clients
    url = f"https://oauth2.googleapis.com/v1/projects/{project_id}/oauthClients"
    # OAuth client creation payload
    payload = {
        "client_name": client_name,
        "redirect_uris": ["https://your-redirect-uri.com"]
    }
    # Define headers for the request
    headers = {
        "Authorization": f"Bearer {credentials.token}",
        "Content-Type": "application/json"
    }
    # Send POST request to create OAuth client
    response = requests.post(url, headers=headers, json=payload)
    # Error handling
    if response.status_code == 200:
        print("OAuth client created successfully.")
        return response.json()
    else:
        print("Error:", response.json())
        return None
# Example usage
project_id = "your-project-id"
client_name = "my-new-oauth-client"
create_oauth_client(project_id, client_name)

// Load Google API client library
gapi.load('client', async () => {
  // Initialize the client with your API key
  await gapi.client.init({
    apiKey: 'YOUR_API_KEY',
    discoveryDocs: ['https://www.googleapis.com/discovery/v1/apis/oauth2/v1/rest']
  });
  // Function to create new OAuth client
  async function createOAuthClient() {
    try {
      const response = await gapi.client.oauth2.projects.oauthClients.create({
        client_name: "my-new-oauth-client",
        redirect_uris: ["https://your-redirect-uri.com"]
      });
      console.log("OAuth client created:", response.result);
    } catch (error) {
      console.error("Error creating OAuth client:", error);
    }
  }
  // Call the function
  createOAuthClient();
});

import unittest
from your_module import create_oauth_client
class TestOAuthClientCreation(unittest.TestCase):
    def test_successful_creation(self):
        result = create_oauth_client("your-project-id", "test-client")
        self.assertIsNotNone(result)
        self.assertIn("client_name", result)
    def test_limit_error(self):
        # Simulate limit error response
        result = create_oauth_client("full-project-id", "test-client")
        self.assertIsNone(result)
if __name__ == "__main__":
    unittest.main()

Understanding the "Reached Limit on Number of Clients" Error in Google Cloud OAuth Setup

One often-overlooked aspect of the “Reached limit on number of clients” error is Google Cloud’s client limit policies, which impose restrictions on how many OAuth clients can be created within a project. Even if a project is new, there may be hidden limitations based on past attempts or accumulated requests. Google imposes these limits to reduce abuse of their API infrastructure, especially for APIs that require sensitive data handling. Consequently, developers setting up projects for Google Assistant on multiple devices, such as TV boxes or IoT systems, may hit these restrictions more frequently than they expect.

Another significant factor that can trigger this error is account-based limitations. Although Google Cloud does allow multiple projects per account, repeated API calls for new projects or clients can raise flags that temporarily lock additional requests. Developers who create multiple projects or switch accounts to troubleshoot may unwittingly trigger rate limits across accounts. To avoid this, you might consider creating OAuth clients only when absolutely necessary and ensuring that old, unused projects are archived or cleaned up. This approach minimizes the strain on Google’s resources and may help prevent the error from reappearing. 🔒

Lastly, this error can be managed by contacting Google Cloud support if you’re encountering the limitation for an essential application. For some developers, upgrading their account or project plan can unlock additional capacity. Although this approach involves cost considerations, it can be a solution for those developing extensive applications that rely heavily on Google Assistant. Being aware of these options and planning around these restrictions can streamline your setup process, giving you fewer headaches in project management and a smoother path to deploying Google’s APIs successfully.