Post jenkins upgrade, windows agent not connecting

Hi,

Recently I upgraded Jenkins from 2.249 to 2.426.1. After that windows agent agent shows offline. Please help with troubleshooting this.

Jenkins setup:

Jenkins: 2.426.1
OS: Linux - 4.14.35-2047.532.3.el7uek.x86_64
Java: 11.0.20 - Oracle Corporation (Java HotSpot™ 64-Bit Server VM)

Office-365-Connector:4.20.2
ace-editor:1.1
active-directory:2.34
ansicolor:1.0.4
ant:497.v94e7d9fffa_b_9
antisamy-markup-formatter:162.v0e6ec0fcfcf6
apache-httpcomponents-client-4-api:4.5.14-208.v438351942757
authentication-tokens:1.53.v1c90fd9191a_b_
authorize-project:1.7.1
basic-branch-build-strategies:81.v05e333931c7d
blueocean-commons:1.27.9
blueocean-core-js:1.27.9
blueocean-dashboard:1.27.9
blueocean-display-url:2.4.2
blueocean-github-pipeline:1.27.9
blueocean-i18n:1.27.9
blueocean-jwt:1.27.9
blueocean-personalization:1.27.9
blueocean-pipeline-api-impl:1.27.9
blueocean-pipeline-scm-api:1.27.9
blueocean-rest:1.27.9
blueocean-rest-impl:1.27.9
blueocean-web:1.27.9
bootstrap5-api:5.3.2-3
bouncycastle-api:2.30.1.77-225.v26ea_c9455fd9
branch-api:2.1144.v1425d1c3d5a_7
build-pipeline-plugin:2.0.1
build-timeout:1.32
build-user-vars-plugin:1.9
caffeine-api:3.1.8-133.v17b_1ff2e0599
checks-api:2.0.2
cloudbees-bitbucket-branch-source:856.v04c46c86f911
cloudbees-folder:6.858.v898218f3609d
codesonar:3.5.0
command-launcher:107.v773860566e2e
commons-httpclient3-api:3.1-3
commons-lang3-api:3.13.0-62.v7d18e55f51e2
commons-text-api:1.11.0-95.v22a_d30ee5d36
conditional-buildstep:1.4.3
config-file-provider:959.vcff671a_4518b_
console-column-plugin:241.va_a_50a_4693b_d2
credentials:1311.vcf0a_900b_37c2
credentials-binding:642.v737c34dea_6c2
custom-job-icon:0.2
custom-tools-plugin:0.8
dashboard-view:2.495.v07e81500c3f2
data-tables-api:1.13.8-2
disk-usage:1.2
display-url-api:2.200.vb_9327d658781
docker-commons:439.va_3cb_0a_6a_fb_29
docker-workflow:572.v950f58993843
durable-task:543.v262f6a_803410
echarts-api:5.4.3-2
email-ext:2.103
envinject:2.908.v66a_774b_31d93
envinject-api:1.199.v3ce31253ed13
extended-choice-parameter:376.v2e02857547b_a_
extended-read-permission:53.v6499940139e5
extensible-choice-parameter:1.8.1
external-monitor-job:215.v2e88e894db_f8
extra-columns:1.26
favorite:2.208.v91d65b_7792a_c
filesystem-list-parameter-plugin:0.0.9
flexible-publish:0.16.1
folder-properties:1.2.1
font-awesome-api:6.5.1-1
git:5.2.1
git-changelog:3.36
git-client:4.6.0
git-server:99.va_0826a_b_cdfa_d
github:1.37.3.1
github-api:1.318-461.v7a_c09c9fa_d63
github-branch-source:1767.va_7d01ea_c7256
github-oauth:597.ve0c3480fcb_d0
github-pullrequest:0.6.1
gradle:2.9
greenballs:1.15.1
groovy:457.v99900cb_85593
gson-api:2.10.1-3.vb_25b_599b_e4f8
handlebars:3.0.8
handy-uri-templates-2-api:2.1.8-30.v7e777411b_148
htmlpublisher:1.32
inline-pipeline:1.0.3
instance-identity:173.va_37c494ec4e5
ionicons-api:56.v1b_1c8c49374e
ivy:2.5
jackson2-api:2.16.1-373.ve709c6871598
jakarta-activation-api:2.0.1-3
jakarta-mail-api:2.0.1-3
javadoc:243.vb_b_503b_b_45537
javax-activation-api:1.2.0-6
javax-mail-api:1.6.2-9
jaxb:2.3.9-1
jdk-tool:73.vddf737284550
jenkins-design-language:1.27.9
jjwt-api:0.11.5-77.v646c772fddb_0
job-dsl:1.87
job-import-plugin:3.6
jobConfigHistory:1229.v3039470161a_d
joda-time-api:2.12.5-5.v5495a_235fedf
jquery:1.12.4-1
jquery-detached:1.2.1
jquery3-api:3.7.1-1
jsch:0.2.16-86.v42e010d9484b_
json-path-api:2.8.0-21.v8b_7dc8b_1037b_
junit:1252.vfc2e5efa_294f
ldap:711.vb_d1a_491714dc
lockable-resources:1222.v3d55a_36d63e4
mailer:463.vedf8358e006b_
mapdb-api:1.0.9-28.vf251ce40855d
mask-passwords:173.v6a_077a_291eb_5
matrix-auth:3.2.1
matrix-project:822.v01b_8c85d16d2
maven-plugin:3.23
mercurial:1260.vdfb_723cdcc81
mina-sshd-api-common:2.11.0-86.v836f585d47fa_
mina-sshd-api-core:2.11.0-86.v836f585d47fa_
momentjs:1.1.1
msbuild:1.30
multi-branch-project-plugin:0.7
multi-agent-config-plugin:1.2.0
multibranch-action-triggers:1.8.6
multibranch-build-strategy-extension:46.v9de263eb_869c
nexus-artifact-uploader:2.14
nodejs:1.6.1
okhttp-api:4.11.0-157.v6852a_a_fa_ec11
pam-auth:1.10
parameterized-trigger:787.v665fcf2a_830b_
pipeline-build-step:540.vb_e8849e1a_b_d8
pipeline-cps-http:0.3.1
pipeline-github:2.8-159.09e4403bc62f
pipeline-github-lib:42.v0739460cda_c4
pipeline-githubnotify-step:49.vf37bf92d2bc8
pipeline-graph-analysis:202.va_d268e64deb_3
pipeline-groovy-lib:689.veec561a_dee13
pipeline-input-step:477.v339683a_8d55e
pipeline-milestone-step:111.v449306f708b_7
pipeline-model-api:2.2168.vf921b_4e72c73
pipeline-model-declarative-agent:1.1.1
pipeline-model-definition:2.2168.vf921b_4e72c73
pipeline-model-extensions:2.2168.vf921b_4e72c73
pipeline-multibranch-defaults:2.1
pipeline-rest-api:2.34
pipeline-stage-step:305.ve96d0205c1c6
pipeline-stage-tags-metadata:2.2168.vf921b_4e72c73
pipeline-stage-view:2.34
pipeline-utility-steps:2.16.0
plain-credentials:143.v1b_df8b_d3b_e48
plugin-util-api:3.8.0
popper-api:1.16.1-3
popper2-api:2.11.6-4
publish-over:0.22
publish-over-ssh:1.25
pubsub-light:1.18
rebuild:330.v645b_7df10e2a_
remote-file:1.24
repository-connector:2.2.1
resource-disposer:0.23
role-strategy:689.v731678c3e0eb_
run-condition:1.7
saml:4.429.v9a_781a_61f1da_
scm-api:683.vb_16722fb_b_80b_
script-security:1310.vf24a_dfce068b_
shared-workspace:1.0.2
simple-theme-plugin:176.v39740c03a_a_f5
skip-certificate-check:1.1
snakeyaml-api:2.2-111.vc6598e30cc65
soapui-pro-functional-testing:1.10
sonar:2.17
sse-gateway:1.26
ssh:2.6.1
ssh-credentials:308.ve4497b_ccd8f4
ssh-slaves:2.947.v64ee6b_f87b_c1
ssh-steps:2.0.68.va_d21a_12a_6476
sshd:3.303.vefc7119b_ec23
structs:325.vcb_307d2a_2782
subversion:2.17.3
timestamper:1.26
token-macro:400.v35420b_922dcb_
trilead-api:2.133.vfb_8a_7b_9c5dd1
uno-choice:2.8.1
variant:60.v7290fc0eb_b_cd
windows-slaves:1.8.1
workflow-aggregator:596.v8c21c963d92d
workflow-api:1283.v99c10937efcb_
workflow-basic-steps:1042.ve7b_140c4a_e0c
workflow-cps:3832.vc43e04d6d68c
workflow-cps-global-lib:609.vd95673f149b_b
workflow-cps-global-lib-http:2.36.0
workflow-durable-task-step:1313.vcb_970b_d2a_fb_3
workflow-job:1385.vb_58b_86ea_fff1
workflow-multibranch:770.v1a_d0708dd1f6
workflow-scm-step:415.v434365564324
workflow-step-api:639.v6eca_cd8c04a_a_
workflow-support:865.v43e78cc44e0d
ws-cleanup:0.45

what is the error in the node log. The issue I have seen for connecting Alma8.8 is that Java version on the node has to match with Java version on Jenkins.
Mine is
java -version
openjdk version “17.0.9” 2023-10-17
OpenJDK Runtime Environment Temurin-17.0.9+9 (build 17.0.9+9)
OpenJDK 64-Bit Server VM Temurin-17.0.9+9 (build 17.0.9+9, mixed mode)

In your case I am thinking your Windows node should have Java: 11.0.20 if that is what the version on your Jenkins server.

After upgrading Jenkins to version 2.426.1, troubleshoot the Windows agent offline issue by verifying network connectivity, ensuring the agent is running a compatible version, checking Java compatibility, reviewing firewall settings, and examining agent logs for error messages. Confirm plugin compatibility, recheck JNLP configuration, and restart the agent service. If issues persist, inspect Jenkins controller logs, attempt node reconnection in the UI, and seek community assistance on forums. Consider temporary plugin disablement and SSL/TLS configuration review. If needed, rollback Jenkins for a quick test and systematically perform these steps to identify and resolve the problem.

I was able to resolve the issues by copying cacerts file from previous/old java home to new java home.