Record Sync : Unable to Sync due to system issue

Question

Facing the following error when creating a new record where record sync is enabled. No recent changes in the code or in the record. 
 The record is marked as synced but its data has not yet been synced. 
 More than 50% of the hard disk space is available in the server. Doesn't seem to be a disk space issue.

Santha · Answer

When I run the sync manually it worked. Looks like Appian infrastructure component had some issue at the time and it got resolved. The record sync and write to record working fine now. Happens to be a temporary server issue.

jaidw · Answer

I recently ran into this exact error message and scenario (writes to DSE consistently caused Record Type's data sync to fail, even though the data changes do get persisted, and manually running a data sync has no problems). In my case, the underlying database table's PK was configured as INT UNSIGNED. When I updated it to be simply INT, the data sync errors on DSE writes went away. 
 I have no idea why the use of UNSIGNED might cause this data sync error, or why Appian might complain about updating " the same entity multiple times in the same transaction ", when that's not what was going on.