Why am I getting "System: System is required." error in JIRA?

[Rex De Silva]

When I am trying to save a user story or bug I get the above "System: System is required." error. What is the cause for this?

If I try to edit a ticket, it works with no issue.

[Nic Brough -Adaptavist- · Accepted solution]

Your system has a custom field called "System", which has been set mandatory in your project's user stories and bugs.  As it's not happening on edit, then it's a validator on "create"

You either need to enter it, or get your admins to change or remove the validator.