What causes a sprint to go from one sprint number to another automatically in the middle of a sprint

Question

Whenever I create a sprint in jira, I set it up for two weeks.  Someone updated the status of a jira ticket in the sprint and it went to a new sprint number and from two weeks to four weeks.  All the other jira tickets also disappeared from the sprint.  What causes this and how do you fix it?

Nic Brough -Adaptavist- · Accepted Answer

Welcome to the Atlassian Community!

This is caused by someone moving the issue from one sprint to another, and then removing all the other issues from the current sprint.

It's an entirely human thing - Jira has no code that moves issues between sprints without it being done by your people.