Salesforce Invalid_Grant Error: Causes, Fixes, and Best Practices

When integrating Salesforce with external applications or APIs, developers often encounter authentication errors. One of the most common OAuth-related issues is the “invalid_grant” error. This error can be confusing because it doesn’t always pinpoint a single cause — it simply indicates that Salesforce rejected the authentication grant.

In this article, we’ll explore what the Salesforce Invalid_Grant error means, its common causes, how to fix it, and preventive measures to ensure seamless integration in the future.

What is the Salesforce Invalid_Grant Error?

The invalid_grant error in Salesforce occurs when an OAuth 2.0 token request fails because the credentials are invalid or expired.

When you try to obtain an access token from Salesforce’s OAuth endpoint (usually /token), Salesforce verifies the refresh token, authorization code, or user credentials. If any part of this process fails validation, it returns:

{
  "error": "invalid_grant",
  "error_description": "authentication failure"
}

This means Salesforce couldn’t authorize the request due to a mismatch or expired token, incorrect redirect URI, or user account issues.

When Does the Invalid_Grant Error Occur?

You might see this error during these scenarios:

1. During OAuth token exchange (authorization code or refresh token).
2. When using Salesforce connected apps for third-party integration.
3. While refreshing expired tokens through an API.
4. When a user’s Salesforce password or security token has changed.
5. During sandbox refreshes or environment migrations.

7 Common Causes of Invalid_Grant in Salesforce

Here are the most frequent reasons for this error:

params = {
"grant_type": "authorization_code",
"client_id": CLIENT_ID,
"client_secret": CLIENT_SECRET,
"redirect_uri": "https://yourapp.com/oauth/callback",
"code": AUTH_CODE
}

How to Fix the Salesforce Invalid_Grant Error?

Here’s a checklist to resolve this issue efficiently:

1. Verify OAuth credentials: Ensure client ID, client secret, and redirect URI are correct.
2. Reauthorize the connected app: If tokens have expired or been revoked.
3. Refresh sandbox or environment settings: Reconnect after a Salesforce sandbox refresh.
4. Check IP addresses and security restrictions; update network access policies as needed.
5. Use tokens promptly: Don’t reuse or delay the use of authorization codes.
6. Update environment variables: Ensure your app uses the latest Salesforce credentials.

import requests
TOKEN_URL = "https://login.salesforce.com/services/oauth2/token"
payload = {
'grant_type': 'authorization_code',
'client_id': 'YOUR_CLIENT_ID',
'client_secret': 'YOUR_CLIENT_SECRET',
'redirect_uri': 'https://yourapp.com/oauth/callback',
'code': 'AUTHORIZATION_CODE'
}

response = requests.post(TOKEN_URL, data=payload)
if response.status_code == 200:
print("Access Token:", response.json()['access_token'])
else:
print("Error:", response.json())

How Moon Technolabs Can Help?

Building and maintaining seamless Salesforce integrations can be complex, especially when handling OAuth flows, token security, and cloud-based synchronization.

At Moon Technolabs, our experts specialize in Salesforce integration, cloud-based automation, and secure API development. We help businesses design robust solutions that minimize authentication errors, such as invalid_grant, and ensure consistent performance across environments.

From token lifecycle management to Salesforce API optimization — Moon Technolabs empowers enterprises with reliable, scalable, and secure cloud integration solutions.

Conclusion

The Salesforce Invalid_Grant error often occurs due to expired tokens, mismatched redirect URIs, or authorization mismatches. While it can seem frustrating, understanding its causes and implementing structured OAuth management can prevent recurring issues.

By following the best practices outlined above — and leveraging expert Salesforce integration support from Moon Technolabs — you can ensure secure, efficient, and reliable cloud-based application performance without interruption.