Starting in the October 2022 release, we introduced a minor change to Marketo REST API response message.


What is changing?

First, let’s begin by looking at the standard defined by the Internet Engineering Task Force (IETF) in RFC 9110


In particular, the standard for Control Data in response messages:

“Response message control data includes a status code, optional reason phrase, and protocol version.”


For example, typical response message control data for a successful HTTP request would be “200” for status code, “OK” for reason phrase, and “HTTP/1.1” for protocol version.


Now, let’s cover what is changing.


The reason phrase will change depending on the deployment of infrastructure.


Why is this change being made?

As part of ongoing maintenance, we must update infrastructure components to newer versions to keep pace with industry change.


What customer action is required?

Action is required if you use an integration that is built using the Marketo REST API and that integration depends on the reason phrase.  If so, then your integration must be changed to remove dependencies on the reason phrase and instead should rely on the status code.   Note that this is an unlikely scenario as most HTTP libraries and integrations already use the status code.


When must customers make the change?

As soon as possible.


What if customers don’t act?

Integrations using the Marketo REST API may not function correctly.