Trying to update ticket through external CSV upload

[Jeremy Price]

When I am trying to update a custom date field via external system upload through CSV type. I receive this message "1000 of 1000 issues have been skipped because they already exist in destination projects." I'm not sure why I am receiving this message. I understand that the ticket already is in the project, all I want to do is update a field. I've done this in the past ( I have issue ID and Issue key listed in my upload sheet) but maybe it doesn't allow me to update a "Dates" custom field the same way.

[Mirek]

I guess that this might be related to Issue ID like in similar topic - https://community.atlassian.com/t5/Jira-questions/Issues-skipped-rather-than-updated-during-External-System-Import/qaq-p/894349