Error 151 occurs when a sync attempt has failed because the record no longer exists on the server. In the log, you will see the message: Sync failed (151) – Record not found.
Typically, this error happens when a record has been deleted from the server, but Pulsar attempted to update that particular record or a related item.
For example, your data may include accounts with client appointments. Your user is offline and creates a client appointment under an account. Meanwhile, someone back at the main office deletes the account. When the user returns online and attempts to sync, the sync fails and returns Error 151.