First error: wbsendit:Too many queueable jobs added to the queue: 2

If you are seeing this error - 

First error: wbsendit:Too many queueable jobs added to the queue: 2

It indicates a process, a flow, or other custom code is triggered when our primary sync runs, which then runs an async job (e.g. batch job or queuable). Essentially this causes a conflict as Salesforce will not allow you to start another job of this type. 

The best next step is to review any custom code or processes that run when our code is executed. Also, look for any triggers, flows, processes, or custom code written against our custom objects.

If you have custom triggers and cannot remove them, consider making this code change - 

if(!system.isFuture() && !system.isBatch())