You receive a notification that the Salesforce sync failed with the error "SalesForce Sync Error: UNABLE_TO_LOCK_ROW"
This indicates that something else in Salesforce was writing to the record at the moment the Marketo Salesforce sync tried to make the update. Since only one "user" at a time can update a record, Marketo was unable to do so and the sync failed.
Marketo will retry an operation a few times if this keeps being received, but will fail and move on if it happens too many times. If these have recently become common, you might want to look into any new API integrations to SFDC which you've deployed or any new AppExchange packages with your SFDC Admin, to see if you might be able to tune it to avoid these collision.
Who This Solution Applies To
Customers integrated with Salesforce