You can download the log files for a job that is running, completed, or failed. Data Loader creates a separate log file for each source object in the task.
You can download a log file from the job details page. You can also download a log file from the subtasks view on the My Jobs, Running Jobs, or All Jobs page.
1Open the My Jobs page in Data Loader, or switch to the Monitor service and open the Running Jobs or All Jobs page.
2In the row that contains the job, click the job instance name to open the job details.
3In the Individual Job Results area, click the Download Session Log icon in the row that contains the source instance you are interested in.