ADDITIONAL SYSTEM INFORMATION :
Windows 10 1803, Java SE Development Kit 10.0.1

Broken: Windows 10 1803 + ő, ű, é or ä
Broken: Windows 10 1511 + ő or ű
OK: Windows 10 1709 + é or ä
OK: Windows 10 1511 + é or ä

A DESCRIPTION OF THE PROBLEM :
The application will not start on Windows 10 1803 if the installation path has non-ascii character.

If the app is installed under C:\Users\User\AppData\Local\FooClient\ then FooClient app will start properly.
If the app is installed under C:\Users\Fréderic\AppData\Local\FooClient\ then FooClient app wont start.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Use Windows 10 Professional 1803, Oracle Java SE Development Kit 10.0.1 and Inno Setup 5.5.9 (u)
2. Source code of the minimum app:

FooClient.java:
import javax.swing.*;

public class FooClient {

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(() -> {
            JFrame frame = new JFrame("HelloWorldSwing");
            frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            frame.pack();
            frame.toFront();
            frame.setVisible(true);
        });
    }
}

3. Build it with the following commands
"C:\Program Files\Java\jdk-10.0.1\bin\javac" FooClient.java
"C:\Program Files\Java\jdk-10.0.1\bin\jar" cfe fooclient.jar FooClient FooClient.class
"C:\Program Files\Java\jdk-10.0.1\bin\javapackager" -deploy -native installer -outdir . -srcdir . -srcfiles fooclient.jar -appclass FooClient -verbose

It produces a native Windows exe package: FooClient-1.0.exe

4. Start the installer on Windows 1803
5. Application is installed under C:\Users\%USERNAME%\AppData\Local\FooClient\
6. If your username has a non-ascii (eg é or ä) character then application will not start.
7.1. Rename C:\Users\%USERNAME%\AppData\Local\FooClient to C:\Users\%USERNAME%\AppData\Local\FooClienté and the C:\Users\%USERNAME%\AppData\Local\FooClienté\FooClient.exe will not start.
7.2. Rename C:\Users\%USERNAME%\AppData\Local\FooClient to C:\Users\%USERNAME%\AppData\Local\FooClienta and the C:\Users\%USERNAME%\AppData\Local\FooClienta\FooClient.exe will start.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Application starts properly even when the path contains non-ascii characters.
ACTUAL -
Application terminates almost immeditely: for a few millisecs there is a running FooClient.exe process but then it terminates.

CUSTOMER SUBMITTED WORKAROUND :
Install application to a directory where the path does not contain ascii characters.

FREQUENCY : always