419 token mismatch error after upgrading to version 11 from 10.

419 token mismatch error after upgrading to version 11 from 10.

A 419 token mismatch error occurs when the server receives a request with a token that does not match the one it expected. This error is commonly encountered after an upgrade from Salesforce Marketing Cloud (SFMC) version 10 to version 11.

The root cause of this error is the change in the way SFMC handles session tokens during an upgrade. In version 10, the session token was included in the URL, while in version 11, it is included in the request header.

To resolve this issue, follow these steps:

1. Update your client applications to include the session token in the request header instead of the URL.

For example, if you are using the REST API, you need to modify your code to include the following header:

X-MC-Session-Token: [Your Session Token]

2. Regenerate your session tokens.

After upgrading to version 11, all existing session tokens become invalid. You need to generate new session tokens using the following API endpoint:

https://[Your Marketing Cloud Account].api.marketingcloud.com/customer/v1/rest/auth/v1/token/request

3. Update your email templates and automation scripts.

Make sure that all your email templates and automation scripts are updated to use the new session token in the request header instead of the URL.

4. Test your applications.

After making these changes, test your applications to ensure that they are working correctly and that the 419 token mismatch error is no longer occurring.

In summary, the 419 token mismatch error after upgrading to SFMC version 11 is caused by the change in the way session tokens are handled. To resolve this issue, you need to update your client applications to include the session token in the request header, regenerate your session tokens, and update your email templates and automation scripts.