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Which Java version for Nuclos? In short: Java 11 (LTS) recommended, Java 8 minimum, Java 17 supported.
REFERENZ BEGINNER UPDATED: JUL 2026 APPLIES TO NUCLOS 4.2026.X
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| Nuclos | Java | Status |
|---|---|---|
| from 4.22 | Java 8 (min. 8u144) | Minimum |
| current | Java 11 (LTS) | Recommended |
| from 4.2023.31 | Java 17 (LTS) | Supported (Rich Client with caveats) |
Info
Nuclos is compatible with OpenJDK – no Java license costs. Use a 64-bit JDK.
Recommendation
Java 11 is an LTS release and currently the best choice for both server and Rich Client.
Java 17 is supported from Nuclos 4.2023.31. Server and Web Client run fully on Java 17; the Rich Client has two known caveats:
With Windows scaling > 100 % the Rich Client UI may look blurry. Fix it via a VM option in the Launcher (Settings > Java configuration > JAVA_VMARGS):
"-Dsun.java2d.uiScale.enabled=false"
For very high-resolution 4K displays, use a fixed scale instead:
"-Dsun.java2d.uiScale=2.0"
If an extension/third-party library reports an InaccessibleObjectException, add the matching --add-opens argument – on the server via the installer (Additional JVM arguments), in the Rich Client via the Launcher (JAVA_VMARGS), e.g.:
--add-opens=java.base/java.net=ALL-UNNAMED
Note
Java 8 is still supported as a minimum but outdated. For new installs we recommend Java 11 or 17.