Class not found: io.jenkins.plugins.casc.model.Mapping

Since the latest release I get this exception.

This is since 1.37, does not occur to my knowledge in 1.36. https://github.com/jenkinsci/configuration-as-code-plugin/compare/configuration-as-code-1.36...configuration-as-code-1.37

YAML lint of configuration file is fine.

org.yaml.snakeyaml.error.YAMLException: Class not found: io.jenkins.plugins.casc.model.Mapping
	at org.yaml.snakeyaml.constructor.Constructor.getClassForNode(Constructor.java:664)
	at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.getConstructor(Constructor.java:322)
	at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:331)
Caused: Can't construct a java object for tag:yaml.org,2002:io.jenkins.plugins.casc.model.Mapping; exception=Class not found: io.jenkins.plugins.casc.model.Mapping
 in /etc/jcasc/jenkins.yaml, line 1, column 1:
    jenkins:
    ^

	at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:336)
	at org.yaml.snakeyaml.constructor.BaseConstructor.constructObjectNoCheck(BaseConstructor.java:230)
	at org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:219)
	at org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:173)
	at org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:157)
	at io.jenkins.plugins.casc.yaml.YamlUtils.loadFrom(YamlUtils.java:127)
	at io.jenkins.plugins.casc.yaml.YamlUtils.loadFrom(YamlUtils.java:112)
	at io.jenkins.plugins.casc.ConfigurationAsCode.configureWith(ConfigurationAsCode.java:608)
	at io.jenkins.plugins.casc.ConfigurationAsCode.configure(ConfigurationAsCode.java:291)
	at io.jenkins.plugins.casc.ConfigurationAsCode.init(ConfigurationAsCode.java:283)
Caused: java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:104)
Caused: java.lang.Error
	at hudson.init.TaskMethodFinder.invoke(TaskMethodFinder.java:110)
	at hudson.init.TaskMethodFinder$TaskImpl.run(TaskMethodFinder.java:175)
	at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:296)
	at jenkins.model.Jenkins$5.runTask(Jenkins.java:1133)
	at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:214)
	at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117)
	at jenkins.security.ImpersonatingExecutorService$1.run(ImpersonatingExecutorService.java:59)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at java.lang.Thread.run(Thread.java:748)
Caused: org.jvnet.hudson.reactor.ReactorException
	at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:282)
	at jenkins.InitReactorRunner.run(InitReactorRunner.java:50)
	at jenkins.model.Jenkins.executeReactor(Jenkins.java:1166)
	at jenkins.model.Jenkins.<init>(Jenkins.java:966)
	at hudson.model.Hudson.<init>(Hudson.java:85)
	at hudson.model.Hudson.<init>(Hudson.java:81)
	at hudson.WebAppMain$3.run(WebAppMain.java:233)
Caused: hudson.util.HudsonFailedToLoad
	at hudson.WebAppMain$3.run(WebAppMain.java:250)

Your checklist for this issue

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• Jenkins version 2.222.1

• Plugin version 1.37

• OS ubuntu:bionic container in ubuntu bionic

Description

Upon fresh-install, I get this exception.

My plugins.txt file:

github-organization-folder
bitbucket-oauth
ws-cleanup
blueocean-git-pipeline
cloudbees-folder
cloudbees-bitbucket-branch-source
pipeline-model-definition
pipeline-stage-tags-metadata
pipeline-input-step
matrix-project
pipeline-github-lib
ssh-credentials
build-timeout
blueocean
matrix-auth
authorize-project
timestamper
credentials
github-branch-source
github
ssh-slaves
docker-plugin
git
bitbucket
hashicorp-vault-plugin
email-ext
configuration-as-code

[timja]

I can reproduce this, downloaded latest version of jenkins, installed suggested plugins, installed jcasc,

added jenkins.yaml:

jenkins:
  systemMessage: testing

[tomlankhorst]

Thank you for your quick response. @timja 's minimal jenkins.yaml triggers this issue indeed.