3100681 - [Import Job History] This action is causing a unique key constraint violation. Check the data

Import job history, download the jobresponse, found the error:

この操作により、キーの一意制約違反が発生しています。データをチェックしてください。

The translation is "This action is causing a unique key constraint violation. Check the data"

SAP SuccessFactors Employee Central, Imports

This exception occurs when same record (same business keys) is being inserted by two parallel transactions. This is being raised to prevent data duplication and to safeguard the system from inconsistencies.

Usually a retry of the second transaction solves this issue. 

This could be any kind of parallel transactions. 
E.g An Import and an API change happening in parallel that modifies the same record, 2 API transactions or an API and UI change etc. 

unique key constraint violation, import error,  , KBA , LOD-SF-EC-EDP , Import Employee Data (EC Core only) , Problem