cannot open file in Downloads folder

[anonymous]

What steps will reproduce the problem?

1. open JOSM
2. click on Open File icon
3. select user/Downloads

What is the expected result?

The program should be able to open the contents of the Downloads folder

What happens instead?

error (i want to attach an image)

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

Relative:URL: ^/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2020-12-28 22:03:23 +0100 (Mon, 28 Dec 2020)
Revision:17428
Build-Date:2020-12-30 02:30:55
URL:https://josm.openstreetmap.de/svn/trunk

Identification: JOSM/1.5 (17428 en) Linux Ubuntu 18.04.5 LTS
Memory Usage: 296 MB / 3916 MB (211 MB allocated, but free)
Java version: 11.0.8+10-post-Ubuntu-0ubuntu118.04.1, Ubuntu, OpenJDK 64-Bit Server VM
Look and Feel: javax.swing.plaf.metal.MetalLookAndFeel
Screen: :0.0 1920×1080 (scaling 1.00×1.00)
Maximum Screen Size: 1920×1080
Best cursor sizes: 16×16→16×16, 32×32→32×32
Desktop environment: ubuntu:GNOME
Environment variable LANG: en_US.UTF-8
VM arguments: [-Duser.home=${HOME}]

Last errors/warnings:
- 00009.691 E: Handled by bug report queue: java.nio.file.InvalidPathException: Malformed input or input contains unmappable characters: /home/<user.name>/Downloads/181026-AI���������������������������.pdf



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

Warning issued by: BugReportExceptionHandler#handleException

=== STACK TRACE ===
Thread: Basic L&F File Loading Thread (57)
java.nio.file.InvalidPathException: Malformed input or input contains unmappable characters: /home/user/Downloads/181026-AI���������������������������.pdf
	at java.base/sun.nio.fs.UnixPath.encode(UnixPath.java:145)
	at java.base/sun.nio.fs.UnixPath.<init>(UnixPath.java:69)
	at java.base/sun.nio.fs.UnixFileSystem.getPath(UnixFileSystem.java:279)
	at java.base/java.nio.file.Path.of(Path.java:147)
	at java.base/java.nio.file.Paths.get(Paths.java:69)
	at java.desktop/sun.awt.shell.ShellFolder.getShellFolder(ShellFolder.java:247)
	at java.desktop/javax.swing.filechooser.FileSystemView.getFiles(FileSystemView.java:523)
	at java.desktop/javax.swing.plaf.basic.BasicDirectoryModel$FilesLoader.run0(BasicDirectoryModel.java:290)
	at java.desktop/javax.swing.plaf.basic.BasicDirectoryModel$FilesLoader.run(BasicDirectoryModel.java:279)
	at java.base/java.lang.Thread.run(Thread.java:834)

[skyper]

Closed as duplicate of #14596.
You need to set a proper LANG= which supports utf-8.