openpty UnsatisfiedLinkError during startup

[BloodEko]

Expected behavior

No error should occur.

Observed/Actual behavior

During startup, an error occurs in the console:

Starting org.bukkit.craftbukkit.Main
Juli 09, 2026 2:01:27 PM org.jline.terminal.impl.ffm.CLibrary <clinit>
WARNUNG: Unable to find openpty native method in static libraries and unable to load the util library.
        - java.lang.UnsatisfiedLinkError: no util in java.library.path: /usr/java/packages/lib:/usr/lib64:/lib64:/lib:/usr/lib
[14:01:27 INFO]: [bootstrap] Running Java...
[14:01:27 INFO]: [bootstrap] Loading Paper...

The error is only visible in the console and not within the logs.

Steps/models to reproduce

Start a server on Linux with the latest jdk-25. On Windows the error doesn't occur.

Paper version

Affected versions:
26.1.2-74
26.2-56

Most recent version:
This server is running Paper version 26.2-56-main@8cd4f47 (2026-07-09T08:35:16Z) (Implementing API version 26.2.build.56-alpha)

Other

On 1.21.11 with Java 21, the error didn't occur.
What causes the error? Has it any effects?

[mbax]

What operating system are you running on? Only instance of this error I can find from jline involves someone running AIX.

[BloodEko]

@mbax It's Ubuntu. Can you eventually explain what the error is about? Then I might be able to help with the research. What changed with Java 25/Minecraft 26.1?

[kennytv]

You should be able to ignore it, but updating our jline dependency might fix it

[BloodEko]

@kennytv Alright. So, you're saying the error is purely cosmetic, without any real impact? Overall, the server boots up and seems to run normally.

[BloodEko]

[00:12:57] [Server thread/INFO]: FifthColumnMC (/213.152.161.54:39237) lost connection: Disconnected
[00:32:07] [Server thread/INFO]: FifthColumnMC (/213.152.161.54:41475) lost connection: Disconnected
[00:39:23] [Server console handler/ERROR]: Caught previously unhandled exception :
java.io.IOError: java.io.IOException: Eingabe-/Ausgabefehler
	at org.jline.keymap.BindingReader.readCharacter(BindingReader.java:170) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.readCharacter(LineReaderImpl.java:901) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.doList(LineReaderImpl.java:4906) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.doList(LineReaderImpl.java:4883) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.doComplete(LineReaderImpl.java:4509) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.doComplete(LineReaderImpl.java:4347) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.completeWord(LineReaderImpl.java:4302) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl$1.apply(LineReaderImpl.java:3778) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.readLine(LineReaderImpl.java:679) ~[jline-reader-3.20.0.jar:?]
	at org.jline.reader.impl.LineReaderImpl.readLine(LineReaderImpl.java:468) ~[jline-reader-3.20.0.jar:?]
	at net.minecrell.terminalconsole.SimpleTerminalConsole.readCommands(SimpleTerminalConsole.java:158) ~[terminalconsoleappender-1.3.0.jar:?]
	at net.minecrell.terminalconsole.SimpleTerminalConsole.start(SimpleTerminalConsole.java:141) ~[terminalconsoleappender-1.3.0.jar:?]
	at net.minecraft.server.dedicated.DedicatedServer$1.run(DedicatedServer.java:175) ~[paper-26.2.jar:26.2-56-8cd4f47]
Caused by: java.io.IOException: Eingabe-/Ausgabefehler
	at java.base/java.io.FileInputStream.read0(Native Method) ~[?:?]
	at java.base/java.io.FileInputStream.read(FileInputStream.java:201) ~[?:?]
	at java.base/java.io.FilterInputStream.read(FilterInputStream.java:71) ~[?:?]
	at org.jline.terminal.impl.AbstractPty$1.read(AbstractPty.java:58) ~[jline-terminal-3.27.1.jar:?]
	at org.jline.terminal.impl.AbstractPty$PtyInputStream.read(AbstractPty.java:124) ~[jline-terminal-3.27.1.jar:?]
	at org.jline.utils.NonBlockingInputStream.read(NonBlockingInputStream.java:62) ~[jline-terminal-3.27.1.jar:?]
	at org.jline.utils.NonBlocking$NonBlockingInputStreamReader.read(NonBlocking.java:157) ~[jline-terminal-3.27.1.jar:?]
	at org.jline.utils.NonBlockingReader.read(NonBlockingReader.java:56) ~[jline-terminal-3.27.1.jar:?]
	at org.jline.keymap.BindingReader.readCharacter(BindingReader.java:160) ~[jline-reader-3.20.0.jar:?]
	... 12 more
[00:39:23] [Server thread/INFO]: Stopping server
...

It actually led to a server shutdown in the middle of the night, with no users online and no visible cause.

[electronicboy]

#14056 - will bump the jline version and should have a jar to test

This is a standard ubuntu kernel running on a standard x86_64 machine? how are you running the jar?

[BloodEko]

[bootstrap] Running Java 25 (OpenJDK 64-Bit Server VM 25.0.3+9-LTS; Eclipse Adoptium Temurin-25.0.3+9) on Linux 5.4.0-231-generic (amd64)

@electronicboy Yes. The jar gets called via screen. Nothing special. On 1.21.11 with Java 21, everything worked without problems.

[BloodEko]

Starting org.bukkit.craftbukkit.Main
Juli 12, 2026 6:55:38 PM org.jline.terminal.impl.ffm.CLibrary <clinit>
WARNUNG: Unable to find openpty native method in static libraries and unable to load the util library.
        - java.lang.UnsatisfiedLinkError: no util in java.library.path: /usr/java/packages/lib:/usr/lib64:/lib64:/lib:/usr/lib
[18:55:38 INFO]: [bootstrap] Running Java 25 (OpenJDK 64-Bit Server VM 25.0.3+9-LTS; Eclipse Adoptium Temurin-25.0.3+9) on Linux 5.4.0-231-generic (amd64)
[18:55:38 INFO]: [bootstrap] Loading Paper 26.2-DEV-HEAD@c420ed4 (1970-01-01T00:00:00Z) for Minecraft 26.2

The error remains on #14056.

[BloodEko]

[19:08:14 INFO]: [ChunkHolderManager] Saved 0 block chunks, 0 entity chunks, 0 poi chunks in world 'minecraft:the_end' in 0,00s
[19:08:14 INFO]: [ChunkHolderManager] Waiting 60s for chunk I/O to halt for world 'minecraft:the_end'
[19:08:14 INFO]: [ChunkHolderManager] Halted I/O scheduler for world 'minecraft:the_end'
2026-07-12T17:08:14.586221900Z Log4j2-AsyncAppenderEventDispatcher-1-Async ERROR An exception occurred processing Appender TerminalConsole
java.lang.IllegalStateException: Terminal has been closed
        at org.jline.terminal.impl.AbstractTerminal.checkClosed(AbstractTerminal.java:796)
        at org.jline.terminal.impl.AbstractWindowsTerminal.writer(AbstractWindowsTerminal.java:242)
        at org.jline.terminal.impl.AbstractTerminal.flush(AbstractTerminal.java:276)
        at org.jline.utils.Display.update(Display.java:786)
        at org.jline.utils.Display.update(Display.java:417)
        at org.jline.reader.impl.LineReaderImpl.printAbove(LineReaderImpl.java:770)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.print(TerminalConsoleAppender.java:263)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.append(TerminalConsoleAppender.java:256)
        at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:160)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:133)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:124)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:88)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatch(AsyncAppenderEventDispatcher.java:178)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatchAll(AsyncAppenderEventDispatcher.java:117)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.run(AsyncAppenderEventDispatcher.java:92)

2026-07-12T17:08:14.587222200Z Log4j2-AsyncAppenderEventDispatcher-1-Async ERROR An exception occurred processing Appender TerminalConsole
java.lang.IllegalStateException: Terminal has been closed
        at org.jline.terminal.impl.AbstractTerminal.checkClosed(AbstractTerminal.java:796)
        at org.jline.terminal.impl.AbstractWindowsTerminal.writer(AbstractWindowsTerminal.java:242)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.print(TerminalConsoleAppender.java:265)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.append(TerminalConsoleAppender.java:256)
        at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:160)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:133)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:124)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:88)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatch(AsyncAppenderEventDispatcher.java:178)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatchRemaining(AsyncAppenderEventDispatcher.java:142)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.run(AsyncAppenderEventDispatcher.java:93)

2026-07-12T17:08:14.588222200Z Log4j2-AsyncAppenderEventDispatcher-1-Async ERROR An exception occurred processing Appender TerminalConsole
java.lang.IllegalStateException: Terminal has been closed
        at org.jline.terminal.impl.AbstractTerminal.checkClosed(AbstractTerminal.java:796)
        at org.jline.terminal.impl.AbstractWindowsTerminal.writer(AbstractWindowsTerminal.java:242)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.print(TerminalConsoleAppender.java:265)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.append(TerminalConsoleAppender.java:256)
        at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:160)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:133)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:124)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:88)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatch(AsyncAppenderEventDispatcher.java:178)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatchRemaining(AsyncAppenderEventDispatcher.java:142)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.run(AsyncAppenderEventDispatcher.java:93)

2026-07-12T17:08:14.589222600Z Log4j2-AsyncAppenderEventDispatcher-1-Async ERROR An exception occurred processing Appender TerminalConsole
java.lang.IllegalStateException: Terminal has been closed
        at org.jline.terminal.impl.AbstractTerminal.checkClosed(AbstractTerminal.java:796)
        at org.jline.terminal.impl.AbstractWindowsTerminal.writer(AbstractWindowsTerminal.java:242)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.print(TerminalConsoleAppender.java:265)
        at net.minecrell.terminalconsole.TerminalConsoleAppender.append(TerminalConsoleAppender.java:256)
        at org.apache.logging.log4j.core.config.AppenderControl.tryCallAppender(AppenderControl.java:160)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender0(AppenderControl.java:133)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppenderPreventRecursion(AppenderControl.java:124)
        at org.apache.logging.log4j.core.config.AppenderControl.callAppender(AppenderControl.java:88)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatch(AsyncAppenderEventDispatcher.java:178)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.dispatchRemaining(AsyncAppenderEventDispatcher.java:142)
        at org.apache.logging.log4j.core.appender.AsyncAppenderEventDispatcher.run(AsyncAppenderEventDispatcher.java:93)

Drücken Sie eine beliebige Taste . . .`

On Windows #14056 performs way worse. Stopping the server via "stop", after the worlds are saved, Log4J complains.

[electronicboy]

The terminal errors on stopping are interesting but not entirely too surprising, cleaning up during the server stopping has long been an issue between the logging stuff closing too early due to how that works and plugins in some looser cases, etc. I wonder if this is an issue primarily due to how old that kernel baseline is

[BloodEko]

https://github.com/jline/jline3

@electronicboy Hard to tell what JLine really needs for which setup. Their documentation just states "JLine 4.x requires Java 11 as the minimum runtime version".

[electronicboy]

Your server isn't breaking on the java part, it's breaking on the "interfacing with the terminal" part