reopen sprint button is not available in my jira instance

[Tejashree Kotkar]

Hello, 

I can not see 'Reopen sprint' option as given in following steps:

"Reopening a sprint

1. Click Boards (in header) > select your desired board.
2. Click Reports, then select Sprint Report.
3. Select the relevant sprint from the sprint drop-down.
4. Click Reopen Sprint. The Reopen Sprint dialog will be displayed, showing you the outcome you can expect when the sprint is reopened.
5. Click Reopen."
   What changes I need to do to make it visible?
   My JIRA instance is 6.4.9 version.

[Nic Brough -Adaptavist-]

You need to upgrade JIRA to a version which includes the function - 7.2 I think.