Paper refused to start on a pre-release Java (Unsupported Java detected)
- Platforms
- Paper · Purpur · single server
- Verified
- Verified
- Confidence
- Confidence 97%
What it looks like in the log
Any one of these lines is enough. The agent matches them locally, on your server.
logs/latest.log
You are running an unsupported, non official, version.
Symptoms
- The server process exits right after launch, before the world and plugins load
- In the panel console: “Unsupported Java detected (…). You are running an unsupported, non official, version.”
Cause
Paper considers the Java build non-GA (java.version contains a “-”, e.g. 25-ea) and exits before the server starts.
Possible causes
- An early-access or nightly JDK build is selected in the image/panel (e.g. 26-ea)
- A beta build of the distribution is in use (a version like 21.0.5-beta)
How to fixLow risk
- Look at the version in brackets in the evidence: the suffixes
-eaand-betamean a non-GA build. - Install a GA Java build of the required version (Paper 1.21.x — Java 21, Paper 26.x — Java 25), e.g. Eclipse Temurin; in the hosting panel, choose a stable Java image.
- The
-DPaper.IgnoreJavaVersion=trueflag disables the check, but Paper only supports GA builds — use it only deliberately and temporarily.
Translated from the Russian original; log lines are quoted verbatim.