Java runtime discovery
scripts/java-runtime.ps1 locates a usable 64-bit Java 25+ executable.
Search order
| Source | Behavior |
|---|---|
| Custom override | Uses java-home.txt or JAROCK_JAVA_HOME when provided. |
| Saved runtime | Reuses the selected absolute executable from local server settings. |
| Environment | Checks JAVA_HOME and PATH candidates. |
| Windows locations | Checks common vendor folders and relevant registry entries. |
| Validation | Runs version, 64-bit, and minimum-version checks before selection. |
When the check fails
The launcher lists candidates that could not be executed or inspected and provides a suggested Java 25 installation path. Java 8 and Java 21 may remain installed; they are rejected for Minecraft 26.2 rather than blindly selected.
If Java is installed in a custom directory, put the JDK folder or its
bin\java.exe path in the root java-home.txt, then run start-server.bat again.Environment automation
When enabled in the parameter manager, Jarock updates only the current user's JAVA_HOME and PATH ordering. It does not uninstall runtimes or modify machine-wide variables.