GanttProject Development Blog

GanttProject 3.4 Beta IV

2026-05-12T01:38:54.216+03:00

GanttProject 3.4 Beta IV is now ready for testing.

This update introduces several workflow refinements and stability fixes in addition to the major features introduced in previous Beta versions — such as the new UI facelift, custom task filters, and auto-resume functionality.

New in Beta IV

Modernized Import/Export

You can now open exported files directly from the Export dialog immediately after saving.
The Import dialog now supports selecting and importing multiple .gan files at once.
Both the Import and Export dialogs have received a UI facelift.

Enhanced Project Insights

We’ve added a new built-in, read-only property, "Is Critical," which identifies if a task is currently on the project's critical path.

Performance and Stability

We have resolved issues that affected stability on computers using non-English locales.

Download the latest build from our website: https://ganttproject.biz/download/gp34

GanttProject 3.4 Beta Release

2026-02-15T00:36:00.001+03:00

GanttProject 3.4 Beta is ready for testing, featuring enhanced customization, a modern UI facelift, and several long-awaited workflow improvements.

Enhanced Customization

Custom Filters: New task filters help you eliminate clutter and focus on what matters.
Calculated Columns: Expressions now support the use of custom columns in calculations.
Visual Charting: Custom columns can now be displayed directly alongside task bars on the Gantt chart.

User Interface & Usability

Modern Look: A refreshed UI and better compatibility with high-resolution screens.
Clickable Links: Web links in the task table are now active, allowing external resources to be accessed instantly.

Installation & Updates

Update Flexibility: Users can now install updates via ZIP files as an alternative to the standard Update Channel.
Linux Support: A new AppImage package is available for easier installation on Linux distributions.

The "Finally!" Feature

Auto-Resume: When GanttProject 3.4 starts, it can automatically reopen your last project. We know you’ve been waiting for this one for a long time! :)

Download GanttProject 3.4 Beta from our official web site: https://ganttproject.biz/download/gp34

GanttProject 3.3 Release

2024-01-30T15:01:00.002+03:00

GanttProject 3.3

We're pleased to share that GanttProject 3.3 is now available for download!

In this update, we bring you:

Calculated Task Columns: Enhance your project data with the ability to calculate custom column values using rich SQL syntax, and gain deeper insights into your project.
Native Package for Apple Silicon: Improved performance on Apple M1 and M2 chips, ensuring a smoother project management experience.
New Filters: Find overdue tasks or tasks due today with ease and gain better control over your project execution and deadlines.

Download GanttProject 3.3 from our web site: https://ganttproject.biz/

GanttProject 3.2: bugfix update 3220

2022-03-01T10:55:00.003+03:00

Second bugfix update to GanttProject 3.2 with a few bugfixes. One of them is critical: it turned out that changes made in the task table cells were not undoable. We highly recommend to install the update.

The update is delivered through the Update Channel.

GanttProject 3.2: first bugfix update

2022-02-26T02:13:00.001+03:00

The first bugfix update to GanttProject 3.2 is published. It includes a few bugfixes, Japanese translation update and a few holiday calendar updates (Brazil, Italy, Spain, Mexico, United Kingdom, United States).

We highly recommend to update your GanttProject because on of the critical fixed issue with resource custom columns.

If Auto-Update is switched on in your GanttProject, you will see the Update Dialog automatically after launching. Otherwise, you can go to the App Updates pane in the Settings Dialog.

The update size is ~8Mb and it installs almost instantly.

GanttProject 3.2 Release

2022-02-16T16:06:00.001+03:00

Hey there,

the release build of GanttProject 3.2 is available for downloading! Read the release notes and watch the video showing the release highlights:

Download packages for Windows, macOS, Linux, and platform-independent ZIP archive from our web site.

GanttProject 3.2 Release Candidate

2022-02-07T19:26:00.001+03:00

A Release Candidate build of GanttProject 3.2 is available for downloading.

The build number is 3.2.3190. You can download it from the public Dropbox folder

It comes as a platform-independent ZIP archive and Java Runtime is NOT included. You have to install Java 11 or Java 17 with JavaFX modules. There are two vendors which provide such Java Runtimes: BellSoft Liberica (choose "Full JRE" package for your platform) and Azul Zulu (choose "JRE FX" package). 

Some tips on running GanttProject from ZIP are available here: https://github.com/bardsoftware/ganttproject/wiki/Installing-from-ZIP

We plan to fix the remaining issues, build packages for all platforms and publish the release build in a few days.

GanttProject 3.1: import resources from the cloud database

2021-05-13T16:03:00.000+03:00

GanttProject 3.1 is just around the corner, and while we're building all the packages, it is a good moment to look at the new feature.

When you write a project file to GanttProject Cloud, we parse and analyze it, extract the resources and store them in a resource database. We use this database e.g. for building a Resource Capacity Heatmap on GanttProject Cloud, and starting from GP 3.1 it can be used to populate projects in GanttProject Desktop. 

Choose "Resources > Add from GanttProject Cloud" from the menu, tick the check boxes next to the people names, hit "Add" and the checked resources will be added to your current project.

This works even if the current project is not yet on the Cloud (and even if it is not planned to be there). You can connect to GanttProject Cloud using a toggle in the status bar. Switch it on to sign in and switch it off to sign out and forget your sign in credentials.

GanttProject 3.0 Release

2021-02-01T04:00:00.000+03:00

Bang! Bang! Meet GanttProject 3.0!

We're starting a new chapter: GanttProject Desktop is now accompanied with GanttProject Cloud, a low-cost solution for the centralized management of team projects and resources. GanttProject 3.0 is the first release which integrates with the Cloud.

We're looking forward for a wonderful and interesting journey!

Meanwhile, some boring details.

Distribution packagesAll packages are available from our web site: https://www.ganttproject.biz/download#download30

Packages for Windows and macOS are bundled with BellSoft Liberica Java Runtime version 11. The download size is about 100Mb and they need about 200Mb of the disk space. 
DEB package for Ubuntu, Mint and other Debian-based Linux systems is not bundled with Java Runtime. It needs a regular Java Runtime 11+ from any vendor, such as AdoptOpenJDK, Amazon Corretto, BellSoft, Azul, etc. 
Platform-independent ZIP package is not bundled with Java Runtime. It needs a Java Runtime 11+ with JavaFX. We're aware of two vendors who provide such Java distros: BellSoft Liberica and Azul Zulu. 

Maintenance updatesWhen we fix a few bugs or update translations or calendars, we publish a maintenance update. Maintenance updates in GP 3.0 are going to be relatively frequent (approximately weekly) and relatively small, and will be delivered through the built-in update channel. We do not plan to publish full packages for each maintenance update, so we highly recommend to keep the auto-update option switched on. 

Feature updatesNew features will be published in feature updates which are going to be less frequent (monthly or bi-monthly) and will be available as full distribution packages.

PricingGanttProject Desktop is free open-source software and is available for any legal purposes and kinds of usage at no charge under GNU General Public License v3. It is okay to use it for free. However, we'll appreciate choosing a pay-what-you-want download option. This will help us to build new features faster. 

You will also help us if you write a review on Facebook, Capterra or G2 or follow us on Facebook or Twitter.

Offline mirror mode when working with GanttProject Cloud

2020-10-14T11:30:00.010+03:00

Many modern project management apps, as well as other software, are built as cloud services. They are great and they work fine, provided that you are online and a lot of servers between your computer and service provider are working normally. They usually do, however, when they don't, it may render very frustrating.

Ooops!

What may go wrong? You Internet service provider may have network issues. Our servers may get down (we do our best to keep them running though!). Even your government may have issues with someone whom you don't even know and may block access to a wide Internet segment because of that.

GanttProject has always been a desktop application and it does not need an Internet connection. But now, when GanttProject Cloud offers a collaborative cloud storage, will it suffer from the same problem of Internet availability? Most likely, no.

GanttProject Desktop app can work with the documents from GanttProject Cloud in two modes: online and mirrored offline. Let's talk a bit about the latter.

The primary storage of a mirrored document is still GanttProject Cloud. When you click Save, you send an HTTP request to our servers and the document is written to the cloud storage. However, it is also saved on your local computer in a slightly hidden place. We call it "mirroring" and we save the file contents and some metadata about the latest sync with the Cloud. Normally this mirror is identical to what is stored in the cloud. It sits in a hidden folder and does not expose itself in any way besides this icon in the status bar:

Status bar indicates if document is available offline

If something wrong happens on the way from you to us, and your desktop GanttProject loses connection with GanttProject Cloud, the document will switch to offline mode and when you click Save, it will write to the local mirror. In the status bar you will see that the document is now Offline and countdown to the next reconnect try

GanttProject is working with the cloud document offline and is trying to reconnect.

Once the connection is restored, GanttProject will try to sync the offline mirror with the Cloud. If Cloud version of the document has not been changed while you were offline, it will just seamlessly switch to online mode, otherwise GanttProject will ask you to resolve the conflict.

GanttProject shows that your offline mirror has diverged from the online copy

But what happens if you close GanttProject when you're offline and then start it again? How can you find your offline mirrors? Don't worry. If you're offline, "GanttProject Cloud" storage in the File Dialog will show your offline mirrored documents.

If you're offline, GanttProject Cloud pane in File Dialog shows offline mirrored documents.

Documents which were accessed in online only mode are naturally unavailable when you work offline. Why one may need online mode then? Well, if you access GanttProject Cloud from a computer which you don't trust, you may want to use the online mode.

You can switch between modes at any moment by clicking the icon in the status bar. It will open a dialog where you can change the online mode, lock or unlock the document or access the revision history.

Starting from update 2911, which is coming soon, GanttProject will open Cloud document in offline mirror mode by default. Have fun, collaborate with your colleagues and build your project plans even when you are offline!

GanttProject 3.0 packaging and update system

2020-09-30T02:27:00.002+03:00

TL;DR: there are many somewhat technical details below. Long story short, GanttProject 3.0 comes with built-in update system. Leave it enabled to get bugfixes and other minor updates faster.

Some 10 years ago GanttProject distro weighed about 10 Mb, in ZIP archive. Installers for Windows and macOS packages contained, basically, the same ZIP distro and platform-specific executable launcher which searched for pre-installed Java Runtime on user's computer. It was easy to install Java Runtime and sometimes Java was even bundled with the operating system.

La belle époque! In 2020 Java software vendors can't rely anymore on Java Runtime availability on the user's computer. There are many technical reasons for that, but let's skip them for brevity. In short, the only reliable way to find suitable Java Runtime on the user's computer is to bring your own one.

So, GanttProject 3.0 for Windows and macOS comes with bundled Java Runtime. It weighs about 100 megabytes. Packages, particularly on macOS, require boring manipulations with signing and notarizing (whatever it means), otherwise the only thing that user is allowed to do with your app is to move it to Trash folder. Building and testing a single release may easily take a day or two. We're fine with doing it once per few months, but it is not really tempting to do it every week. On the other side, we'd like to be able to iterate quickly and publish updates frequently.

That's why we implemented our own simple update system in GanttProject 3.0.

User interface informs about the availability of new updates.

GanttProject since version 2.0 internally was built from a few modules which are managed by a small kernel code. The modules are just folders on disk with some zipped libraries and XML files inside. The kernel scans a couple of known folders, detects modules and runs code from them.

In GP 3.0 we added versions to modules and now when the kernel finds two modules with the same id, but different versions, it takes the one with the highest version number. Our modules now look like a sort of stacked layers.

An example of the base version 2906 with some updates up to 2910

This rather simple modification turned out very powerful. We can build a new version of a single module put it next to the existing versions and -- voilà! -- when GP launches, it uses the new version. We can remove a few latest versions from the disk and thus rollback to some previous version.

From the user perspective, when GanttProject 3.0 is starting, it contacts our download server, downloads a list of updates, compares it with what is already installed and, should it find a new update, asks the user if they want to install it.

There is no hidden automated installation or downloading the updates in the background. It is relatively easy to roll back. We can fix a bug and deliver it to the users in the matter of hours, and it actually happened in the latest build 2910. A sad issue with CSV export and import on some locales where decimal separator is different from dot (e.g. comma) was fixed and published about 7 hours after reporting.

We plan to use these updates to deliver bugfixes, localization and calendar updates just like we did with the minor releases in GanttProject 2.X series. Major updates will come in a full distribution.

Download GanttProject 3.0, let it update to the latest build and have fun!

GanttProject 3.0 beta, build 2910

2020-09-29T19:25:00.000+03:00

We started a public beta testing of GantProject 3.0 in August. The testing goes fine, we already see a few dozens of people who use GP 3.0 is their daily work. GanttProject 3.0 is compatible with our old good GP 2.X series and it reads and writes files in the same format. It is also very stable, so we encourage to join the beta testing.

Due to many factors, we had to include Java Runtime into the distributions, and the size of GanttProject 3.0 distro is now about 100 megabytes. Because of this and because building a complete distro for all platforms takes a lot of time, we decided to implement the update system which can install small updates as they are ready.

So, today we published update 2910 with many bugfixes and usability improvements. If you launch GP 3.0, the update system will suggest to install this update, as well as the previous ones.

Work with file storage was rewritten in GP 3.0 and now documents from the local computer, from WebDAV storages and from our own GanttProject Cloud are available in the single File Dialog. It is already very nice and became even better in build 2910:

Offline cloud documents support is nearly completed. We fixed a lot of bugs, made the user interface more intuitive and checked that GP switches between offline and online modes smoothly (and fixed it when it didn't). Offline cloud documents are great, and we'll share more details on this later.
Cloud documents were seamlessly integrated into the Recent Documents list.
Work with local documents became more error-proof. "Save" button becomes disabled if the target file can't be written, and we show a hint explaining the reasons. "Overwrite" checkbox prevents from accidental overwriting of the existing files.

Local documents in the File Dialog

GanttProject Cloud document in the Recent Documents list

Download GanttProject 3.0, update to the latest build and join beta-testing! GanttProject 3.0 is integrated with GanttProject Cloud server for storing your project documents. if you work in a team, don't miss the opportunity to try GP Cloud. It is free during the beta-testing.

GanttProject 2.8.11 hotfix update

2020-05-02T02:00:00.000+03:00

A new build 2396 of GanttProject 2.8.11 is available from our website: https://www.ganttproject.biz/download

It fixes a few severe issues:
-- macOS: only English, Galician and Tajik languages are available in the settings UI;
-- Linux: ganttproject launcher won't open files when using relative paths;
-- all platforms: visible columns in the task and resource tables reset to default after undo operations or on file opening;

Version number remains the same, only build number has changed.

If you already downloaded GP 2.8.11-r2393, we strongly recommend to download the new build.

GanttProject 2.8.11

2020-04-22T12:00:00.000+03:00

GanttProject 2.8.11 is a maintenance release with updated calendars, translations, a few fixed bugs and major update in macOS package.

Updated holiday calendars of top 20+ countries and regions according to our Google Analytics data. Welcome, Karnataka region!
Major update of Simplified Chinese translation and minor updates in Korean, Italian and Turkish translations.
Several fixed bugs.
Package for macOS now comes with bundled Java Runtime and is properly signed and notarized to make the security system in the latest macOS versions happy.
Also, we tested a number of Java Runtime configurations on Windows and wrote up the results in the release notes to help our users choose the runtime which provides the best experience.

Packages for Windows, macOS, Ubuntu/Mint/Debian Linux and platform-independent ZIP archive
are available from the download page on ganttproject.biz and from the release page on GitHub.

GanttProject is free software and you can download any package at no cost. You can help us to spread the world by leaving your like or review on Facebook or Capterra or by following us on Twitter or Facebook, or by purchasing paid download.

GanttProject is now available from Microsoft Store

2020-03-02T16:02:00.000+03:00

GanttProject application with bundled Java Runtime is now available from Microsoft Store. We hope that this will make it easy to install on portable Windows devices, such as Microsoft Surface.

Please notice that this app is marked as unofficial. It was packaged by Hauke Hasselberg independently on his own initiative, and we can't provide support with respect to packaging issues, should they arise. However, it is the same GanttProject which you can download from our official locations and we do provide the same best-effort support for packaging- and device-independent functionality.

GanttProject 2.8.10

2019-01-30T22:48:00.000+03:00

GanttProject 2.8.10 comes with updated holiday calendars for 20+ countries and regions where most of our users come from (welcome Mumbai and Zurich regions!). It also fixes a number of bugs and usability issues. See the full list of bugfixes.

Packages for Windows, macOS, Ubuntu/Mint/Debian Linux and platform-independent ZIP archive are available from the download page on ganttproject.biz.

GanttProject is free software and you can download any package at no cost. You can help us to spread the world by leaving your like or review on Facebook or Capterra or by following us on Twitter or Facebook, or by purchasing paid download.

GanttProject 2.8.9: bugfixes

2018-08-23T02:29:00.002+03:00

GanttProject 2.8.9 fixes a number of bugs, including a very annoying bug with task names being truncated to the first few symbols in table cells. The full list of fixed issues is available from our GitHub pages.

There is also German translation update and new Dutch and Israel holiday calendars.

Download

Packages for Windows, macOS, Ubuntu/Mint/Debian Linux and platform-independent ZIP archive are available from the download page on ganttproject.biz.

GanttProject 2.8.8: better usability, compatibility and localization

2018-05-22T14:38:00.001+03:00

GanttProject 2.8.8 is here with a bunch of important updates. Thanks everyone who sent us bug reports and participated in testing!

Here is a brief overview of the updates.

Usability

First, annoying behavior of selection and cell editing in the task table which was introduced in 2.8.7 is now fixed. We also added some padding around cell values to separate adjacent right- and left- aligned cells.

Tasks in the predecessor dropdown in the task properties are now indented according to WBS and prefixed with task ID.

Compatibility

It turned out that GanttProject had issues when running under Java 10: MS Project import/export didn't work and macOS users had issues with launching GanttProject by double-clicking gan files. These issues are solved in 2.8.8. Besides, macOS users can now drag tasks on the chart using mouse with Command key hold. On other platforms it works with Control key hold but on macOS Ctrl+mouse click would show a context menu.

Export/Import enhancements

Two columns were added to CSV export/import: task color and resource load on particular tasks. The latter can be used for your own calculations of the total resource loads and costs in spreadsheets and databases. This column is called Assignments and it accompanies older column Resources, so you will find them both in the produced CSV files.

The values in Assignments column are semicolon-separated pairs of resource id and load which are in turn colon-separated. Thus, the value 1:50.00;2:100.00 means that the load of resource with id "1" in this task is 50%, while resource 2 works 100% of his time.

Import from Microsoft Project now recognizes recurring holidays in the default project calendar.

Localization

Great news for Chinese, Japanese and Korean users: task table in PDF reports is expected to be fixed and should show symbols properly, provided that you use an appropriate embeddable application font. On the screenshot below WengQuanYi Micro Hei font was used.

New holiday calendar for South Korea has been contributed by one of our users.

Bugfixes

Weird bug "no enum constant" which appeared when reading certain projects is now fixed. Another very annoying issue with adding whitespace in task notes on Windows platforms is fixed as well.

Download

Packages for Windows, macOS, Ubuntu/Mint/Debian Linux and platform-independent ZIP archive are available from the download page on ganttproject.biz.

GanttProject 2.8.7

2018-04-18T20:24:00.002+03:00

GanttProject 2.8.7 download is available!

In this update mouse wheel behavior made more consistent with other apps and GanttProject itself.

Mouse wheel rotation will vertically scroll chart no matter if the mouse pointer is over the table or chart area.
If Shift is hold, mouse wheel will scroll a chart horizontally.
If Ctrl is hold mouse wheel rotation will change zooming.

We also restored a keyboard shortcut Ctrl+Space which expands/collapses task nodes. Discover other useful shortcuts which will make you more productive!

There is a number of bugfixes and updated translations, with major updates in Japanese and Catalan.

If you want new updates and features to appear faster and better, please fund the development and buy GanttProject for your platform from our online shop:

* Installer for Windows
* Package for Mac OSX
* Package for Ubuntu/Mint/Debian
* Platform-independent ZIP package

We love getting paid, but still want to highlight that GanttProject is free. You can download it at no cost from our website. You can help us to spread the world by leaving your like or review on Facebook or Capterra or by following us on Twitter or Facebook.

GanttProject 2.8.6

2018-02-13T01:54:00.001+03:00

GanttProject 2.8.6 is available for downloading.

In GP 2.8.6 cross-window clipboard made working. You can now copy tasks and resources between GanttProject windows using standard copy/paste operations. In the previous versions one had to import the whole project to copy the data.

GanttProject 2.8.6 also includes a number of bugfixes, more than dozen holiday calendar updates (welcome Alberta, Canada and three Australian states) new Indonesian translation and a few other translation updates.

If you want to fund the development, buy GanttProject for your platform from our online shop:

* Installer for Windows
* Package for Mac OSX
* Package for Ubuntu/Mint/Debian
* Platform-independent ZIP package

We love getting paid, but still want to highlight that GanttProject is free. You can download it at no cost from our website and help us by leaving your like or review on Facebook or Capterra.

GanttProject 2.8.5: task sorting

2017-05-19T19:09:00.001+03:00

We're glad to announce GanttProject 2.8.5 which comes with a new feature: task ordering by begin/end dates. The feature itself was highly demanded, but what makes it even more exciting is that it is the first published feature which has been contributed by external freelancer and funded by the donations from GanttProject users. A number of other paid features is already done in the main branch and will be published in the next major update.

Sample project with tasks sorted by begin date

If you love GanttProject and want new features to be added faster, donate as much as you want!

Task sorting

Sorting should work as expected: click the column header to sort in ascending order, click again to toggle to descending order.

The sort order is partial. Sibling tasks are sorted, while tasks from different branches of the task tree (e.g. sitting under different summary tasks) are not necessarily sorted. For instance, on the screenshot above milestone "GanttProject 2.8.5" goes below the child tasks of "Architectural design", although it starts earlier. The order is indicated with an arrow in the column header showing upwards when order is ascending or downwards when it is descending.

Sorting is not maintained continuously. Any actions on the tasks such as insertion of the new task, reordering, indenting and outdenting may break the sort order. One needs to click in the column header again to restore the ordering.

Besides the new feature, GanttProject 2.8.5 fixes a few severe bugs and updates Korean and Dutch translations.

Download GanttProject from the official web site

Follow GanttProject on Twitter and Facebook.

Meet new support forum

2017-03-27T14:56:00.002+03:00

We launched a renewed support forum on https://help.ganttproject.biz

Our old home-grown organic forum.ganttproject.biz have been working fine for years requiring almost no maintenance, but time flies and modern forum software provides nice features which had no chances to appear on forum.ganttproject.biz. So, we're running now our own instance of great open-source forum Discourse and it is our default go-to place for support.

Old forum will remain alive for quite a while. It is even in read-write mode now, however it will go read-only soon.

GanttProject 2.8.4: scalable UI on high-density screens and bugfixes

2017-03-27T12:57:00.000+03:00

We released GanttProject 2.8.4 which greatly improves UI scalability on high-density devices such as MacBook with Retina screen and Windows Surface Pro.

DPI option in GanttProject settings is now considered in the most major aspects of the user interface, including toolbar buttons and milestones and arrow shapes on the chart. This means that the whole application can be scaled by a simple change of DPI value in the settings.

The absolute majority of the users should be happy with the default value of 96. Those who use high-density displays are advised to set the value to something close to the real DPI of their screens. Values in the range 150-220 shall be good.

We recommend to set Normal size of Application and Base chart fonts and adjust them only for fine tuning. Bigger DPI value and smaller application font size may produce good results in some use cases.

Settings dialog with DPI option

Changing DPI option is safe: it only linearly scales fonts and graphics in GanttProject and doesn't affect operating system or Java Runtime. However, we recommend to restart GanttProject after changing DPI option value.

In unfortunate case when fonts appear so small that it is hard even to change the DPI value, one can edit the settings file manually. The settings file is named .ganttproject (note the leading dot, such files may be hidden by the operating system) and it sits in the user home folder. It is a text file which can be edited in any text editor. Adding this line between any other option tags will set DPI to 120:

<option id="ui.screenDpi" value="120"/>

You need to close all GanttProject windows before editing the settings file.

Besides the scalability, GanttProject 2.8.4 fixes a few bugs and gets back iCal import plugin.

Download GanttProject from the official web site

Follow GanttProject on Twitter and Facebook.

Troubleshooting MS Project import: shifted dates

2017-03-10T17:24:00.002+03:00

This page describes possible reasons of task dates change after import from MS Project file.

While we do our best to import MS Project files as is, you may notice that after import some of the tasks change their dates. The reason is that Microsoft Project and GanttProject are different applications with different features and different behavior. If you see a warning saying that some of the tasks changed their dates, you may use the list below as a guide to fixing this issue. We recommend to start from the earliest task because it might turn out the cause of changes in the whole subsequent chain.

So, why a task may change the dates after import:

In the original MS Project file it starts on weekend day and you import it into a project with non-working weekends. In this case you need to choose "replace existing calendar" option in the importer or import into project with working weekends
In the original MS Project file tasks have dependency with a lag. GanttProject by default makes the project as short as possible and when it can remove the lag, it will. In this case you need to set default dependency hardness to "Rubber" in the Gantt chart settings before you import a project.
In the original MS Project file tasks have duration less than 1 day and/or task starts on the same day when its predecessor ends. GanttProject's duration granularity is 1 day, and it assumes that task starts in the morning and finishes in the evening, so it is impossible for successor to start at the same day when predecessor finishes. You can set a negative lag in the dependency properties to fix it for the given pair of tasks, but GanttProject won't do it automatically during the import
Microsoft Project is known to be somewhat forgiving with respect to dependencies, and it is possible that task with e.g. Finish-Start dependency on its predecessor actually starts earlier than predecessor finishes in the original file. GanttProject is more strict and enforces the constraint.

You may also find useful our docs on the scheduling algorithm in GanttProject.

GanttProject 2.8.3: how to get back ical import

2017-03-08T15:44:00.000+03:00

Update: this bug is fixed in GanttProject 2.8.4

Due to a bug in the application configuration import from iCal is missing in GanttProject 2.8.2 and GanttProject 2.8.3. If you want to get it back, do the following (applies to 2.8.3):

Open file plugins-2.8.3/biz.ganttproject.impex.ical/plugin.xml
from your GanttProject 2.8.3 installation in any text editor (you may need Administrator/root priveleges for that)
At line 9 replace ganttproject-ical.jar with biz.ganttproject.impex.ical.jar
Save the file and restart GanttProject

On Mac OSX the file sits in /Applications/GanttProject.app/Contents/Java/plugins-2.8.3/biz.ganttproject.impex.ical/ provided that GanttProject is installed in Applications

Sorry for this issue! We'll fix the distributions in the next update.