The content of this Space is not the latest version of WBS Gantt-Chart for Jira.
We have separate Space for each version of the product. If the version you are using differs from the one in this Space title, please find the correct one from the below page.
https://rssupport.atlassian.net/wiki/spaces/WGC/overview
Users of Version x.x.x6a or earlier may lose data if they do not uninstall first
Summary
If you have an old version of WBS Gantt-Chart for Jira (x.x.x6a or earlier), make sure you uninstall this before reinstalling the latest version. You may lose data otherwise.
Workaround
See above.