SFDC OAuth Redirect Failure Error

[#1]

Summary

Disable Require PKCE for syncing with SFDC via OAuth 2.0

Issue

If attempting to connect Marketo to Salesforce via OAuth 2.0, no authentication window is presented by Salesforce allowing for credentials to be entered, only showing "Redirect Failure"

Environment

Marketo is not compatible with the "Proof Key for Code Exchange" authentication with Salesforce, "Require PKCE" in Salesforce Configurations

Solution

Disable the "Require PKCE" checkbox in the Connected App during configuration of OAuth 2.0, prior to connecting Marketo via the Native SFDC Integration.

Root Cause

PKCE not supported by Marketo's sync solution with Salesforce. This is documented in Adobe Experience League: Log in Using OAuth 2.0 | Adobe Marketo Engage