The steps in Set Up Marketing Cloud Connection in Data 360 outline how to setup a connection from Data 360 to Marketing Cloud Engagement. During this process you must authenticate with the username and password of a Marketing Cloud Engagement user. That user's credentials are then used by the connection when ingesting data to Data 360 and activating data to Marketing Cloud Engagement.
As outlined in Marketing Cloud Security Setting, the setting User Passwords Expire In policy results in user passwords expiring after a set amount of time. If the password of the user whose credentials are used by this connection between Data 360 and Marketing Cloud Engagement expires, you will see activations start to fail in your Data 360 with the error "Change your expired Marketing Cloud password and try again".
Note: to prevent this from happening, consider enabling the policy Exclude API Users from Password Expiration in Marketing Cloud and using the credentials of an API User for this connection. This setting can be viewed/modified in Marketing Cloud Engagement by your Marketing Cloud Admin navigating to Setup | Security | Security Settings | Exclude API Users From Password Expiration
To resolve this issue, you will need to login to Marketing Cloud Engagement with the credentials of the user that was used when connecting your Data 360 to Marketing Cloud Engagement, which will then allow you to reset the expired password.
Follow these steps to complete this action:
This error can also occur for activations when the Marketing Cloud Engagement user has been disabled. If you are not able to login with the user's credentials, you will need to confirm in Marketing Cloud Engagement if the user is disabled and re-enable the user to be able to re-authenticate from Data 360. Review the steps in Disable a Marketing Cloud User, which also includes the steps to re-enable a disabled user.
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