Jenkins started failing to do new builds due to Kubernetes lately

[skjagini]

Hi

I have Jenkins running on Kubernetes as per this repo, started noticing from yesterday that my builds are failing due to the following error
Seen branch in repository origin/master
Seen 1 remote branch
Obtained Jenkinsfile from 190653029108941c19b8f712b77cab8a5c2cdb3a
Running in Durability level: MAX_SURVIVABILITY
org.codehaus.groovy.control.MultipleCompilationErrorsException: startup failed:
WorkflowScript: 8: Invalid agent type "kubernetes" specified. Must be one of [any, docker, dockerfile, label, none] @ line 8, column 5.
kubernetes {
^

1 error

at org.codehaus.groovy.control.ErrorCollector.failIfErrors(ErrorCollector.java:310)
at org.codehaus.groovy.control.CompilationUnit.applyToPrimaryClassNodes(CompilationUnit.java:1085)
at org.codehaus.groovy.control.CompilationUnit.doPhaseOperation(CompilationUnit.java:603)
at org.codehaus.groovy.control.CompilationUnit.processPhaseOperations(CompilationUnit.java:581)
at org.codehaus.groovy.control.CompilationUnit.compile(CompilationUnit.java:558)
at groovy.lang.GroovyClassLoader.doParseClass(GroovyClassLoader.java:298)
at groovy.lang.GroovyClassLoader.parseClass(GroovyClassLoader.java:268)
at groovy.lang.GroovyShell.parseClass(GroovyShell.java:688)
at groovy.lang.GroovyShell.parse(GroovyShell.java:700)
at org.jenkinsci.plugins.workflow.cps.CpsGroovyShell.doParse(CpsGroovyShell.java:142)
at org.jenkinsci.plugins.workflow.cps.CpsGroovyShell.reparse(CpsGroovyShell.java:127)
at org.jenkinsci.plugins.workflow.cps.CpsFlowExecution.parseScript(CpsFlowExecution.java:561)
at org.jenkinsci.plugins.workflow.cps.CpsFlowExecution.start(CpsFlowExecution.java:522)
at org.jenkinsci.plugins.workflow.job.WorkflowRun.run(WorkflowRun.java:327)
at hudson.model.ResourceController.execute(ResourceController.java:97)
at hudson.model.Executor.run(Executor.java:427)

Finished: FAILURE

On Jenkins I see the following warning:
Kubernetes plugin version 1.25.0
You must update Jenkins from version 2.204.5 to version 2.217 or later to run this plugin.

I even updated my GCP Kubernetes latest available version (1.15.9-gke.22) to see if this issue can be mitigated

Has anyone faced similar issue? Did upgrading Jenkins worked for you (any instructions as say to upgrade ). Thanks