Gradle quarkusRun: invalid null character in command

[rodcheater]

Describe the bug

Running ./gradlew quarkusRun on a new Quarkus project fails with java.io.IOException: invalid null character in command.

Expected behavior

Gradle quarkusRun succeeds.

Actual behavior

Gradle quarkusRun fails.

How to Reproduce?

Steps to reproduce

1. Create a new Quarkus project using Gradle as the build system: quarkus create app --gradle
2. Run quarkusRun: cd code-with-quarkus && ./gradlew quarkusRun

Expected result

The app starts running.

Actual result

Gradle fails with java.io.IOException: invalid null character in command.

Output of uname -a or ver

Darwin Rods-MacBook-Pro.local 24.5.0 Darwin Kernel Version 24.5.0: Tue Apr 22 19:52:00 PDT 2025; root:xnu-11417.121.6~2/RELEASE_ARM64_T6031 arm64

Output of java -version

openjdk version "21.0.7" 2025-04-15 OpenJDK Runtime Environment Homebrew (build 21.0.7) OpenJDK 64-Bit Server VM Homebrew (build 21.0.7, mixed mode, sharing)

Quarkus version or git rev

3.23.0

Build tool (ie. output of mvnw --version or gradlew --version)

Gradle 8.8

Additional information

No response

[quarkus-bot]

/cc @glefloch, @quarkusio/devtools

[mstoeckel]

any resolution or workaround for this problem?

[reaver585]

Hi everyone. I can reliably reproduce this issue, and I'm looking into it. It seems to be Mac specific, and I have some leads to follow.
I will get back to you all once I have some updates.

[reaver585]

There seem to be multiple layers to this issue. Here's a summary:

Quarkus CLI

When creating a new Quarkus project using Gradle and the Quarkus CLI, the generated gradlew script includes the following snippet:

# For Darwin, add options to specify how the application appears in the dock
if $darwin; then
    GRADLE_OPTS="$GRADLE_OPTS \"-Xdock:name=$APP_NAME\" \"-Xdock:icon=$APP_HOME/media/gradle.icns\""
fi

I suspect the JVM transforms the -Xdock:icon property into an environment variable like APP_ICON_{PID}.

However, this shouldn't be happening - those Darwin-specific lines were removed from the Gradle wrapper 4 years ago.

SmallRye Config

This conflicts with smallrye-config, which transforms all env vars into lowercase, dotted config keys. The transformation method seems to have a bug - keys ending with an underscore followed by digits may introduce null characters.

When running ./gradlew quarkusRun, the QuarkusRun task (which uses Java's ProcessBuilder) fails due to this:

if (s.indexOf('\u0000') >= 0) {
    throw new IOException("invalid null character in command");
}

TL;DR

• I'll submit a bug report to smallrye-config for the env var format that introduces null characters.
• The Quarkus CLI appears to generate a project with an outdated Gradle wrapper - this likely deserves a separate issue.
• For now, you can work around the problem by upgrading the Gradle wrapper in the generated project:

$ ./gradlew wrapper --gradle-version {YOUR_VERSION}

Ensure the version is >= 7.2.0 to avoid the problem.

I suggest keeping this issue open for now.

[aloubyansky]

@reaver585 thanks a lot for the thorough investigation!
@radcortez fyi about the SR Config issue.

[radcortez]

Fix from SR Config: smallrye/smallrye-config#1364

[reaver585]

Thanks a lot, @radcortez!