Helix with JDTLS doesn't provide any LSP features

[nthcristian]

Summary

When working on a Java project with JDTLS, no LSP features are shown. For example, pressing <space>-k opens an empty pop-up and <space>-a always tell me there are no code actions available. Also, there's no code errors or warnings inside a file.

Reproduction Steps

I tried this:

1. Open Helix in a folder with a Java Gradle project (JDK25).
2. Tried using any LSP features.

I expected this to happen:
Errors (like writing Strng instead of String) should show up. I should be able to inspect objects, find definitions and execute code actions.

Instead, this happened:
No LSP features were available.

Helix log

~/.cache/helix/helix.log

File was too long to paste:
helix.log

Platform

Linux (archlinux:base-devel container on podman/CachyOS)

Terminal Emulator

kitty/fish

Installation Method

yay (AUR)

Helix Version

Helix 25.07.1

[waddie]

Around line 1072 jdtls is complaining about not being able to use Java 25.0.4 and Gradle 8.9 to import the project. Gradle added Java 25 support in 9.1.0. Do you need to upgrade Gradle or downgrade your JDK?

Looks more like a workspace issue than a Helix bug. Do you have the same problem with a minimal hello-world.java in a temp directory?

[nthcristian]

Gradle version

$gradle --version

------------------------------------------------------------
Gradle 9.6.1
------------------------------------------------------------

Build time:    2026-06-27 12:31:14 UTC
Revision:      <unknown>

Kotlin:        2.3.21
Groovy:        4.0.32
Ant:           Apache Ant(TM) version 1.10.17 compiled on April 6 2026
Launcher JVM:  25.0.4 (Arch Linux 25.0.4)
Daemon JVM:    /usr/lib/jvm/java-25-openjdk (no Daemon JVM specified, using current Java home)
OS:            Linux 7.1.5-1-cachyos amd64

Java version

$java --version

openjdk 25.0.4 2026-07-21
OpenJDK Runtime Environment (build 25.0.4)
OpenJDK 64-Bit Server VM (build 25.0.4, mixed mode, sharing)

JDTLS version

# Couldn't find an internal version option
$pacman -Qi jdtls

Name            : jdtls
Version         : 1.60.0-1
Description     : Eclipse Java language server
Architecture    : any
URL             : https://github.com/eclipse/eclipse.jdt.ls
Licenses        : EPL-2.0
Groups          : None
Provides        : None
Depends On      : java-runtime>=21
Optional Deps   : python: for the official launcher script [installed]
Required By     : None
Optional For    : None
Conflicts With  : None
Replaces        : None
Installed Size  : 52.04 MiB
Packager        : Unknown Packager
Build Date      : Wed Aug 5 20:04:51 2026
Install Date    : Wed Aug 5 20:07:54 2026
Install Reason  : Explicitly installed
Install Script  : No
Validated By    : None

I created a new Gradle project using gradle init with the default options, including the default testing framework, and got the same result.

Then I created a new container with the jdk21-openjdk package installed, while keeping the same Gradle and JDTLS versions, and Helix worked correctly.

Maybe Helix is picking up the wrong Gradle version somehow?

I also tried removing ~/.eclipse, which appears to be created by JDTLS, but that didn't help either.

Logs from test project

helix.log

[waddie]

Do you have Gradle Wrapper setup in the project? Try cat gradle/wrapper/gradle-wrapper.properties, if that exists it should show you the version the project is using.

If your JAVA_HOME is Java 25 and gradle-wrapper.properties references 8.9, that would explain the mismatch. gradle wrapper --gradle-version 9.1.0 will bump it to the first Java 25 compatible version.

[nthcristian]

I do. Here’s my gradle-wrapper.properties:

distributionBase=GRADLE_USER_HOME
distributionPath=wrapper/dists
distributionUrl=https\://services.gradle.org/distributions/gradle-9.6.1-bin.zip
networkTimeout=10000
retries=0
retryBackOffMs=500
validateDistributionUrl=true
zipStoreBase=GRADLE_USER_HOME
zipStorePath=wrapper/dists

I also deleted the entire gradle/wrapper directory and ran gradle wrapper to recreate it, but I’m still getting the same result.