| | 19 | == Headless runtime error or !NoClassDefFoundError |
| | 20 | |
| | 21 | If !WorldPainter does not start, and gives one the following errors on the console or in the log file: |
| | 22 | |
| | 23 | {{{ |
| | 24 | The Java runtime (...) is headless. |
| | 25 | }}} |
| | 26 | |
| | 27 | or: |
| | 28 | |
| | 29 | {{{ |
| | 30 | Exception: java.lang.NoClassDefFoundError thrown from the UncaughtExceptionHandler in thread "AWT-EventQueue-0" |
| | 31 | }}} |
| | 32 | |
| | 33 | then this means that !WorldPainter can't find a complete Java runtime with GUI support. Some distributions, such as Fedora, have a "headless" Java runtime environment installed by default, which only supports console applications, but not graphical user interfaces. |
| | 34 | |
| | 35 | If this is the case, then you need to manually install a complete Java runtime, either a JRE or a JDK. For Fedora for example, the command for this would be: |
| | 36 | |
| | 37 | {{{ |
| | 38 | sudo dnf install java-21-openjdk |
| | 39 | }}} |
| | 40 | |
| | 41 | For other distributions a similar command will be available. For the Java version it is recommended to use the latest LTS version. |
| | 42 | |
