JOSM requires a recent version of Java 6 runtime environment to be installed on your computer.
JOSM is also compatible with Java 7 and we encourage you to update to this version for security reasons, as Oracle stopped the support of Java 6 in March 2013. We plan to switch to Java 7 some day, see #8465.
If you have only Java 5 and cannot update, there are older versions of JOSM available: Version 3377 and below runs with Java 5. Old versions of JOSM, including Mac and Windows installers, are available in the download archive.
If you have only an old version of Java 6 (older than update 27, released in August 2011), you can run the latest version of JOSM, but you may face one of the following Java bugs. To get rid of it, please perform the corresponding update actions.
- #8387: Ubuntu: Dialog moves down in Ubuntu Unity -> Install latest Ubuntu updates (see Ubuntu bug 1110138)
- #8182: Mac OS: Cannot open files in directories with swedish characters in them -> Update to Java 7 update 10 or later (see Java bug 7193966)
- #7206: All OS: Cannot load preferences.xml -> Update to Java 6 update 14 or later (see Java bug 6708840)
- #6993: Ubuntu: Tooltips not displayed at the right place -> Install latest Ubuntu updates
- #6989: Ubuntu: Bad links sent to browser -> Install latest Ubuntu updates
- #6965: Windows: Error when using File/Save As -> Upgrade to Java 7 (see Java bug 6210674)
- #6769: Ubuntu: Download window initialization error -> Install latest Ubuntu updates or upgrade to Java 7 (see Java bug 6523403)