Error when trying to open a subfolder

[troels@…]

What steps will reproduce the problem?

1. Use File -> Open...
2. Select a subfolder

What is the expected result?

The subfolder opens.

What happens instead?

An error dialog pops up.

Please provide any additional information below. Attach a screenshot if possible.

The subfolder contains a file called "Den himmelblå.zip". The "å" character is expressed as hex values C3 A5. That should be OK for UTF-8, but it seems to be an issue in JOSM, so it cannot open the subfolder.

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2026-03-28 20:28:41 +0100 (Sat, 28 Mar 2026)
Revision:19555
Build-Date:2026-03-29 01:30:57
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (19555 en) Linux Arch Linux
Memory Usage: 319 MB / 1954 MB (204 MB allocated, but free)
Java version: 21.0.11+10, Arch Linux, OpenJDK 64-Bit Server VM
Look and Feel: javax.swing.plaf.metal.MetalLookAndFeel
Screen: :0.0 2560x1440x[Multi depth]@60Hz (scaling 1.00×1.00)
Maximum Screen Size: 2560×1440
Best cursor sizes: 16×16→16×16, 32×32→32×32
Environment variable LANG: da_DK.UTF-8
System property file.encoding: UTF-8
System property sun.jnu.encoding: ANSI_X3.4-1968
Locale info: en_US
Numbers with default locale: 1234567890 -> 1234567890
Desktop environment: KDE

Last errors/warnings:
- 00109.509 E: Handled by bug report queue: java.nio.file.InvalidPathException: Malformed input or input contains unmappable characters: ${HOME}/Downloads/Den himmelbl��.zip



=== REPORTED CRASH DATA ===
BugReportExceptionHandler#handleException:
No data collected.

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: Basic L&F File Loading Thread (69)
java.nio.file.InvalidPathException: Malformed input or input contains unmappable characters: /home/troels/Downloads/Den himmelbl��.zip
	at java.base/sun.nio.fs.UnixPath.encode(UnixPath.java:129)
	at java.base/sun.nio.fs.UnixPath.<init>(UnixPath.java:76)
	at java.base/sun.nio.fs.UnixFileSystem.getPath(UnixFileSystem.java:313)
	at java.base/java.nio.file.Path.of(Path.java:148)
	at java.base/java.nio.file.Paths.get(Paths.java:69)
	at java.desktop/sun.awt.shell.ShellFolder.getShellFolder(ShellFolder.java:260)
	at java.desktop/javax.swing.filechooser.FileSystemView.getFiles(FileSystemView.java:585)
	at java.desktop/javax.swing.plaf.basic.BasicDirectoryModel$FilesLoader.run0(BasicDirectoryModel.java:307)
	at java.desktop/javax.swing.plaf.basic.BasicDirectoryModel$FilesLoader.run(BasicDirectoryModel.java:298)
	at java.base/java.lang.Thread.run(Thread.java:1583)

[troels@…]

Screenshot

[GerdP]

See

System property file.encoding: UTF-8
System property sun.jnu.encoding: ANSI_X3.4-1968

This error is reported again and again and is always closed as a duplicate of #14596. I wonder if there is really no way to ignore the wrong system configuration ANSI_X3.4-1968 ?