A deadlock occurs when two or more sessions are waiting for data locked by each other, resulting in all the sessions being blocked. Oracle automatically detects and resolves deadlocks by rolling back the statement associated with the transaction that detects the deadlock.  In terms of Team Approach, an example scenario would be if two Account Data Upload jobs were running simultaneously on different queues (which is not recommended) and one job locked interactions data and the other job locked transactions data. Then each job attempted to access the records that the other job was holding. 
In general, locks are useful and necessary in that that they ensure data read/write consistency by not allowing one session to change information while another is in the process of changing it.  Deadlocks are pretty uncommon because Team Approach doesn't generally use whole table locks, so if this occurs, it generally indicates that two processes were looking at the same section of two tables simultaneously. The solution is to rerun the process with the deadlock error.
If you encounter this error, please create a support request at www.blackbaud.com/support providing the the details of the job and log, referencing this solution.

In the case of the error in the Synch log, it was probably caused by a process running in TA at the time (i.e.  ADU job), so the sync and ADU just deadlocked and the sync was killed. It happens from time to time with different versions of the sync. The Synch job should run fine next time.