macOS Platform specific instructions

Modelio requires that a JDK 8 be installed to work properly (not only JRE) [JDK 8 download page]. Please note that Modelio is not compatible with newer versions of the JDK so you need to install the JDK 8 (macOS supports the installation of different versions of the JDK).

On macOS, a *.dmg file is provided, which contains modelioX.Y.app (for example Modelio 3.8.app).

Open the *.dmg then drag&drop Modelio X.Y (for example Modelio 3.8) on your desktop.

If you don't have the JDK 8 installed or if it is not correctly configured you will see this error:
modelio high sierra error

For fixing this error, we propose an automatic procedure or a manual one.

Automatic procedure

We made a script in order to fix this error.
Unzip the following archive in the same folder as Modelio X.Y.app. It contains scripts for different versions of Modelio (from Modelio 3.6). Just run once the right script that matches your version of Modelio in a Terminal.
For example bash .fixModelio38.sh for Modelio 3.8

macos fix modelio38

Modelio should run fine after that.

Manual procedure

Instead of running the above script you can fix the error manually.

Right-click on Modelio X.Y app and run the Show package contents command:

show package contents

Then, edit the 'Modelio X.Y/Contents/Eclipse/modelio.ini' with a text editor that doesn't add formatting characters like paragraphs (avoid to use TextEdit. You can use nano from a Terminal or some code editors like Atom, JEdit, ...)

explorer modelio

Your 'modelio.ini' file should have this content:

-startup
../Eclipse/plugins/org.eclipse.equinox.launcher_1.3.201.v20161025-1711.jar
--launcher.library
../Eclipse/plugins/org.eclipse.equinox.launcher.cocoa.macosx.x86_64_1.1.401.v20161122-1740
-clearPersistedState
-vmargs
-Xms512m
-Dpython.console.encoding=UTF-8
-XstartOnFirstThread
-Dorg.eclipse.swt.internal.carbon.smallFonts

 You should add

-vm 
/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home/bin/java
after -clearPersistedState (Please note the /Library/Java... line has to be adapted to match the JDK installation path of your computer) and
-Dosgi.requiredJavaVersion=1.8
after -vmargs so you have the following result:
-startup
../Eclipse/plugins/org.eclipse.equinox.launcher_1.3.201.v20161025-1711.jar
--launcher.library
../Eclipse/plugins/org.eclipse.equinox.launcher.cocoa.macosx.x86_64_1.1.401.v20161122-1740
-clearPersistedState
-vm 
/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home/bin/java
-vmargs
-Dosgi.requiredJavaVersion=1.8
-Xms512m
-Dpython.console.encoding=UTF-8
-XstartOnFirstThread
-Dorg.eclipse.swt.internal.carbon.smallFonts

 Save and close the ini file then you should be able to run Modelio fine.