GanttProject crashes whenever I edit a task

Hi, Just started to use GP on my new laptop with Windows 10. I’ve used it on a desktop with Windows 10 and 7 without this issue.

The issue is that I can’t edit the duration, links or move tasks around in the time line window. I can add more tasks in the left hand column and change the colour and whether they are a milestone or task, but I can’t do anything with the duration or predecessors, etc. Anything that seems to change the timeline view just doesn’t show once the change has been made.

When it crashes, the timeline window just freezes and I can move the list view on the left up and down the task list without the timeline moving at the same time.

Java is saying there’s no update and I have the latest 2.8.10 version of GanttProject. Any ideas why this is doing this on the laptop but not the desktop?


This usually happens when the structure of your tasks is malformed and there is a sort of dependency loop which moves tasks far apart of each other and thus makes the project excessively wide, which in turn makes the chart renderer thinking. Please share your project file to check this.

However, there might be other issues which are laptop specific. You may try reading our Knowledge Base articles in particular this one

Hi Dmitry,

Thanks for the reply. It seems I may have worked out the issue.

I have a task group called Deliverables, and within this I have a number of Milestones for when each part of the project would be delivered. It doesn’t like moving the milestones within a task group as the project duration increases.

If I move the milestones out of the sub-group they work fine. So I can’t keep all the milestones in one group they have to be entities on their own.

Can I not group the milesstone together?


Milestones per se do not make any difference. Their dependencies is what matters. Most likely you have something like dependency from a milestone to its super-task which makes a dependency loop. When you move milestones out, you break the loop.

Thanks. It appeared to be a link between two super-tasks where the lower super task, containing milestones, needed to overlap the one above with the main tasks. I didn’t think I’d done anything too challenging for it, and it was just an erronous link when I made the super-task. :roll_eyes:
All sorted!
Thank you for the help.

Seems I have a similar issue, but my problem is that ganttproject will crash when I open the file. So I can’t even rectify.

Any chance to rectify? Otherwise I have to make the whole plan again.
Unfortunately can’t share the file here.


Is it reproducible with just a single file? Please send it to us by email.
You may also post the contents of your log file. You can find it in your home directory. Its name is ganttproject.log on Windows and macOS