REST API Double Slash Deprecation

[KeithGluck]

On September 16, 2025, Adobe transitioned to a more modern hosting infrastructure for REST API URLs that leverages newer technology, adding security and scalability.

If your subscription has been using APIs with a double forward slash (//) in the URL, you should have received the following alert in Marketo Engage, with a Learn More link:

It is possible not everyone received or noticed the alert, as we recently discovered some existing API URLs have been generating 500 server errors, due to the API call itself. If you were affected by this, to resolve the error, you must modify the URL of the API call to change the double slash (//) to a single slash (/) where applicable.

Which API endpoints are impacted and should be modified?
Any Marketo REST APIs that include a double slash (//) in the URL.

What happens if we didn't make any changes prior to the deprecation date?
Those specific APIs will fail; data synchs, Lead updates, or Campaign Triggers (depending on those specific calls) will not execute successfully. Additionally, monitoring or automation pipelines relying on those pipelines may show errors or experience delays.

We didn't see or receive that alert. What action should we take?
-Locate URLs by reviewing API endpoint configurations and integrations in the codebase to search for double slashes.
-Normalize the impacted URLs by ensuring their calls are modified as recommended.
-Apply URL sanitation logic, especially where they are dynamically generated from environment variables, base URLs, or paths.
-Validate post-fix calls – use a test call to confirm that endpoints are working after the fix.

How can we get guidance on this deprecation?
For self-service:
-Review API logs if logging is in place to look for errors (if logs are not accessible, contact Adobe Support for assistance).

Should changes be made in a Sandbox environment first?
Yes, it is highly recommended to make changes in a Sandbox environment (if applicable) prior to making changes in production.
Once these changes are made, any ongoing failures due to double slash URLs should be resolved and processes should run back to normal.

What if we have more questions, or don't want to go the self-service route?
If you need assistance or have any additional questions, please reach out to your Account Representative or Adobe Support at any time.