You should contact Ancestry support. there is a little bit of software you can run to capture your errors and send to the support folks.
Also, these user groups are filled with people having sync problems, though not necessarily the same error message you got.
I personally have not been able to sync for the last 2 months. I re-downloaded my database fresh several times, but every time I try to sync, I get an error that says there was a sync error. Can't get past it.
Last contact I had from Ancestry support said to be patient that they are working on the sync issues ...