While you modify an issue in JIRA Client, it can be simultaneously modified on JIRA server by somebody else. When you upload the modified issue to the server (for example, by clicking the Upload Changes button on the issue toolbar), JIRA Client verifies the updated attribute of this issue on the server. If it does not detect any changes, the local changes are uploaded, and the issues get synchronized. If JIRA Client detects the differences between the server and the local copy, it warns you about a possible conflict.
Firstly JIRA Client tries to merge the following issue properties automatically:
All read-only information (not modifiable in JIRA Client, like permissions or available workflow actions),
Votes and voters list,
Watched issues information,
Comments,
Attachments,
Links,
Parent task (if the issue is a sub-task),
Work logs,
Time spent,
Custom fields where multiple values are allowed (like multiple selection).
If other issue properties were modified concurrently:
In conflict icon appears in Flags column of the Issues table and in the status bar which means the same as Locally modified issue state plus that the issues upload failed due to a conflict.
