After upgraded to JIRA/JIRA Agile new release, found that the all burndown charts of old released versions disappear in 'Release Board'.
Before JIRA Agile v5.0, as the below instructions shown in Planning Board Guide, when users release a version in JIRA Agile, the relevant charts of that version can be saved for the future review in Release Board. And, to support this function, JIRA Agile saves those release version charts as the graphic files under <JIRA_Home_Directory>/caches/Charts, and re-generate charts based on those files for uses' future review. However, if <JIRA_Home_Directory> is changed in JIRA upgrade, JIRA Agile can not find those saved graphic files under the new <JIRA_Home_Directory>, so the charts of old released versions are lost in Release Board.
To resolve this issue, you may need to copy "caches/Charts" folder from the old <JIRA_Home_Directory> to newone.
Since the implementation of released version charts has been enhanced in JIRA Agile 5.0, which doesn't depend on graphic files any more, you will not run into this problem when you upgrade JIRA Agile from 5.0+ releases.