Nucleus: Error: Could not find or load main class com.aws.greengrass.easysetup.GreengrassSetup.

[eduelias]

Describe the bug
While trying to run the command:

java -jar "/var/greengrass/v2/GreengrassInstaller/lib/Greengrass.jar" \
--init-config "/var/greengrass/v2/GreengrassInstaller/config.yaml" \
--setup-system-service true \
--trusted-plugin "/var/greengrass/v2/GreengrassInstaller/aws.greengrass.FleetProvisioningByClaim.jar"

On Fedora-IoT 42 (OpenJDK21), we get the error:

Error: Could not find or load main class com.aws.greengrass.easysetup.GreengrassSetup
Caused by: java.lang.ClassNotFoundException: com.aws.greengrass.easysetup.GreengrassSetup

While on Fedora-IoT 41 (OpenJDK11) the command works fine.

To Reproduce
Using Fedora-IoT 42 (OpenJDK21) image, try to run the command with default values, the error happens.

Expected behavior
To run install Greengrass and run the FleetProvisioning plugin.

Actual behavior
Tell us what actually happened.

Environment

• OS: Fedora Linux 42.20250601.0 (IoT Edition)
• JDK version: 21
• Nucleus version: 2.15.0

Additional context
Again, we've been using the same configs/jars with Fedora 41 (OpenJDK11) with no issues.

E.g. what is the impact of the bug?
We have 1100 Automated Parcel Lockers in The Netherlands that are missing updates and configuration because they cannot have their OS Updated because of this problem.

[alter-mage]

Hi, thanks for bringing this to our attention. I am working on reproducing this.

[alter-mage]

What version of Nucleus and Fleet Provisioning By Claim plugin are you using? Could you also provide the contents of your installation configuration file? This is the file that you provided with the --init-config parameter.

Additionally,

1. Are you downloading the Nucleus and Fleet Provisioning By Claim artifacts from the recommended sources, ie, cloudfront?
2. Has fleet provisioning worked for you on any other device? Or previously on the same device?

[junfuchen99]

Do you know the specific build version of your openjdk 21? Is your device arm64 or x86_64?

[eduelias]

Sorry about the delay, I took some time off ...
I'm managing 1500 devices (Automated Parcel Lockers) using greengrass, and all of them have from 2.14.0 to 2.15.0 nucleus version. I tested on all available, 2.14.X to 2.15.0 and all of them fail when using openjdk 21.
Here's my current "test-subject" spec:
Nucleus: 2.14.1
Our devices are RPi CM3+, so, arm64.
We're using Fedora-IoT 41 and 42. (Great majority using 41, as 42 doesn't have the jdk11).
We have downloaded them from Cloudfront/AWS indeed. And we use greengrass to update nucleus.
We have it working on JDK11, never on 21.

This is our provisioning config.

services:
  aws.greengrass.Nucleus:
    configuration:
      interpolateComponentConfiguration: true
      jvmOptions: "-XX:+UseSerialGC -XX:TieredStopAtLevel=1"
      logging:
        level: INFO
        outputDirectory: "/var/greengrass/v2/logs"
        outputType: FILE
      runWithDefault:
       posixUser: "ggc_user:ggc_group"
  aws.greengrass.FleetProvisioningByClaim:
    componentType: PLUGIN
    configuration:
      awsRegion: "eu-west-1"
      claimCertificatePath: "/var/greengrass/v2/claim-certs/claim.pem.crt"
      claimCertificatePrivateKeyPath: "/var/greengrass/v2/claim-certs/claim.private.pem.key"
      iotCredentialEndpoint: "REDACTED.credentials.iot.eu-west-1.amazonaws.com"
      iotDataEndpoint: "REDACTED-ats.iot.eu-west-1.amazonaws.com"
      iotRoleAlias: "aple-ggv2-token-role-alias"
      provisioningTemplate: "aple-ggv2-provisioning-template"
      rootCaPath: "/var/greengrass/v2/AmazonRootCA1.pem"
      rootPath: "/var/greengrass/v2"
      templateParameters:
        SerialNumber: "998877_000000009f2667e6"
system:
  rootCaPath: "/var/greengrass/v2/AmazonRootCA1.pem"
  rootPath: "/var/greengrass/v2"

[robcmann]

Hello, I have been investigating the ClassNotFoundException on Fedora IoT 42 with OpenJDK 21, but I have not been able to reproduce this issue in my test environment. In my attempts, I used both Fedora Linux 42.20250903.0 (IoT Edition) and 42.20250601.0 (IoT Edition) in combination with OpenJDK 21.0.8 2025-07-15 and Nucleus 2.15.0 on an ARM64 device. Both of these tests were able to provision and start Greengrass successfully.

While we continue to investigate, would it be possible for you to update Fedora IoT 42 and OpenJDK 21 to their latest respective versions in case this is an environment-specific issue? This may resolve the issue if it's environment-specific.