If an error occurred, the very last output of emchain will be something like
emchain: BEWARE: One or more of the tasks ended in error !You should then look into the log file for a specific message like
emchain: BEWARE: That task ended in error !The associated messages may help you understand what happened. If the error occurred in the last exposure, the intermediate files will not be erased, you may also inspect them (if they were erased, rerun emchain for the particular instrument and exposure where the error occurred, setting stoponerror=Y).
If you think you have found a workaround (editing a file for example), you may relaunch the task which ended in error, duplicating the call written after 'CMD:' in the log file. You may also relaunch emchain from the intermediate files (see example above).
If the error is of general significance (not just a corrupted file at your site), feel free to send an Observation Report.
