major enhancement 
enhancement
major bug fix 
bug fix
major enhancement enhancement
major bug fix bug fix
= I use it on my production site without major issues. 
= I don't recommend it. 
= I tried it but rolled back to a previous version. Action could cause an entire REST export response to fail.
Upgraded to Stapler 1.250 with a fix.
(issue 40088)
H is handled correctly in preview.
(issue 26977)
IllegalStateException from Winstone when making certain requests with access logging enabled.
(issue 37625)
hudson.model.ParametersAction.keepUndefinedParameters property is set to false.
(pull 2687)
JENKINS_HOME disk space threshold from 1Gb to 10Gb left.
The warning will be shown only if more than 90% of the disk is utilized.
(issue 40749)
ClassNotFoundException: javax.servlet.ServletException error
when invoking shell tasks on remote agents.
(issue 40863)
POST flag in ManagementLinks within the Manage Jenkins page.
(issue 38175)
Reload from disk management link.
(pull 2692)
Inject Build Variables flag was not set.
(issue 39268)
Errors and Exceptions.
(issue 39835)
hudson.slaves.ChannelPinger.pingIntervalSeconds and
hudson.slaves.ChannelPinger.pingTimeoutSeconds
system properties.
(issue 28245)
SlaveComputer instances when possible.
(issue 40286)
-noCertificateCheck warning to STDOUT.
(pull 2666)
Manage Jenkins page into admin monitor.
(issue 39433)
config.xml write operations.
(issue 40435)
Check for Updates button in the Plugin Manager was hidden in the Updates tab
when there was no plugins updates available.
(issue 39971)
ProxyException now retains info about suppressed exceptions
when serializing over the channel.
(remoting pull #136)
Jenkins#isSubjectToMandatoryReadPermissionCheck(String restOfPath) method
for checking access permissions to particular paths.
(issue 32797)
Node#getNodeProperty() methods for retrieving node properties.
(issue 40365)
Items#allItems() methods for accessing items in item groups without sorting overhead.
(issue 40252)
KeepBuildForever.
(issue 40281, regression in 2.34)
QueueTaskDispatcher extension, NodeProperty and other extensions.
(issue 38514)
UserProperty.setUser(User).
(issue 40266)
Action retrieval methods.
It speeds up core and plugin logic operating with Actionable objects like items, folders, nodes, etc.
(issue 38867)
1.7 to 1.8.
The change disables obsolete Ciphers: AES128CBC, TripleDESCBC, and BlowfishCBC.
(issue 39805)
1.22 to 1.24.
Full changelog is available here, only major issues are mentioned below.
(pull 2619)
killRecursive.
It was likely impacting process termination on Windows agents.
(WinP Issue #22)
remoting.jar/slave.jar there.
(pull 2633)
FATAL: Invalid object ID 184 iuota=187 and java.lang.Exception: Object was recently deallocated.
(issue 23271)
hudson.showWindowsServiceInstallLink property from the slave-agent.jnlp file.
It was causing harmless security warnings in Java web start.
(issue 39883)
3.0.
Upgraded to Remoting 3.1 with a fix.
(issue 39596, regression in 2.26)
NullPointerException when rendering CauseOfInterruption.UserInterruption
in build summary pages for non-existent users.
(issue 38721 and
issue 37282,
regression in 2.14)
ResourceBundleUtil#getBundle().
(issue 39604)
ExtensionList.removeAll was not unimplemented in Jenkins extension management API.
It was causing issues during dynamic loading of GitHub and BitBucket branch source plugins on the same instance.
(issue 39520)
hudson.remoting.Engine (mostly Java Web Start) was failing to establish connection
if one of the URLs in urls parameter was malformed.
(issue 39617)
org.jenkinsci.remoting.nio.NioChannelHub.disabled flag
for disabling NIO, mostly for debugging purposes.
(issue 39290)
IOHub concurrent thread number spikes.
(issue 38692)
Actionable initialization changes made for issue 39404).
It caused massive regressions in plugins like Jenkins Pipeline.
(issue 39555, regression in 2.29)
1.246 caused regressions in plugins depending on Ruby Runtime Plugin.
Upgraded to Stapler 1.248 with a fix.
(issue 39414, regression in 2.28)
2.16, a reconfiguration may be required.
(issue 39465)
Warning! This release is not recommended for use due to issue 39555 and issue 39414. We are working on the out-of-order release (discussion).
1.246 caused regressions in plugins depending on Ruby Runtime Plugin.
Upgraded to Stapler 1.247 with a partial fix.
(issue 39414, partial fix)
onOnline() handler.
(issue 38487)
since tag.
(Stapler pull #84)
2.7.1 to 2.14.
Changelog is available here.
(pull 2606)
1.2-beta-4 to 1.6.
Changelog is available here.
(pull 2606))
JNLPComputerLauncher (e.g. from Slave Setup, vSphere Cloud and other plugins).
No the connection is accepted from launchers implementing other proxying and filtering Launcher implementations.
Particular plugins may require setting up the
jenkins.slaves.DefaultJnlpSlaveReceiver.disableStrictVerification system property in the master JVM to allow connecting agents.
(issue 39232, regression in 2.28)
hudson.XmlFile#readRaw() in the case of encoding issues.
(issue 39363)
LargeText.BufferSession.skip(), which was causing hanging of Pipeline jobs in corner cases.
(issue 37664)
1.243 to 1.246 with fixes required for the Blue Ocean project.
More details are coming soon.
Raw changes are listed here.
(pull 2593)
4.0-beta to 4.0.
This change required upgrade of detached plugins (see above).
(pull 2568)
slave.jar now explicitly require Java 7.
(issue 37565)
ResourceBundleUtil.
It fixes internationalization in Blue Ocean
and Jenkins Design Language.
(issue 35845)
TopLevelItemDescriptor#getIconFilePathPattern() and switch to IconSpec.
(issue 38960)
CommandInterpreter build steps to set a build result as Unstable via the return code.
Shell and Batch build steps now support this feature.
(issue 23786)
MaskingClassloader.
(issue 23784)
XStream driver to improve performance of XML serialization/deserialization.
(pull 2561)
-noKeepAlive option.
(issue 38539)
NullPointerException in Engine#connect()
when host or port parameters are null or empty.
(issue 37539)
hpi:record-core-location during the build in order to enabled coordinated run across repositories.
(pull 1894)
@since definitions in Javadoc.
(pull 2578)
jenkins.model.Jenkins.slaveAgentPortEnforce system property, which prevents slave agent port modification via Jenkins Web UI and form submissions.
(PR #2545)
jenkins.model.Jenkins on agents in the ProcessKillingVeto extension point.
(issue 38534)
jenkins.model.Jenkins.slaveAgentPort system property, which was not honored.
(issue 38187, regression in 2.0)
java.io.StreamCorruptedException: invalid stream header: 0A0A0A0A.
(issue 23232)
userContent/readme.txt.
(PR #2532)
UpdateSite#getJsonSignatureValidator() can be now
overridden and used in plugins.
(PR #2532)
Cloud.PROVISION permission independent from Jenkins.ADMINISTER.
(issue 37616)
null CRON specifications in build triggers.
(issue 36748, enhances fix in 2.15)
ComboBoxList element in order to make options visible.
(issue 37549)
AntClassLoader being used in the core.
(issue 37561)
jenkins.install.InstallUtil.lastExecVersion file
in JENKINS_HOME.
(issue 37438)
IllegalStateException.
(issue 33549)
Queue#maintain() message for dead executors during task mapping
from INFO to FINE.
(PR #2510)
ChangeLogAnnotator API usage in plugins.
Enhances JENKINS-23365 fix in 1.569.
(issue 36757)
onClose() listener writes to the already closed log.
(issue 37098)
jenkins.slaves.JnlpSlaveAgentProtocol3.enabled
system property.
(issue 37315)
?uctest parameter to HTTP and HTTPS URLs only.
(issue 37189)
SCM Retry Count field is empty.
(issue 36387)
NullPointerException in the BlockedBecauseOfBuildInProgress build blockage cause visualization.
(issue 36592)
quiet-down and cancel-quiet-down were extracted from the core to CLI.
(issue 35423)
ComputerSet#getComputerNames() method.
(issue 35423)
ItemCategory#MIN_TOSHOW in external plugins is now restricted.
(issue 36593)
IllegalStateException under certain conditions when reloading configuration from disk while jobs are in the queue.
(issue 27530)
DescriptorVisibilityFilters for ComputerLauncher, RetentionStrategy and NodeProperty.
(issue 36280)
NullPointerException during SCM polling if SCMDecisionHandler returns null veto.
(issue 36232, regression in 2.11)
SCMDescriptor.newInstance overrides are honored when creating new SCM entries.
(issue 36043,
issue 35906
, regression in 2.10)
BUILD_TAG environment variable description to mention the replacement of slashes with dashes.
(PR #2417)
BulkChange auto-closeable.
(PR #2428)
SecurityRealm returns null when loading a user.
(PR #2407)
NullPointerException in user registration if user ID is not specified.
(issue 33600)
no_proxy environment variable.
(issue 32326)
hudson.Remoting.Engine#waitForServerToBack now uses credentials for connection.
(issue 31256)
TaskListener creation to build agent implementations.
(issue 34923)
UpdateSites to tweak the InstallationJob.
(issue 35402)
NullPointerException on startup after update from Jenkins 2.5.
(issue 35206)
hudson.model.Run or hudson.model.Job).
Regression in Groovy 2.4,
see GROOVY-7826 for more info.
(issue 34751)
PingFailureAnalyzer for agent=>master ping failures.
(issue 35190)
DelegatingComputerLauncher now accepts child classes in its hooks
(pre-offline, pre-connect, etc.).
(issue 35198)
SystemInfoLink.
(PR #2375)
InstallState and InstallStateFilter extension points.
(PR 2281 as supplementary change for
issue 33663)
ParametersAction.
It simplifies fixing of plugins affected by SECURITY-170 fix.
(PR 2353)
ParametersDefinition and BuildDiscarder properties.
(PR 2358)
online-node CLI command for accepting multiple agents.
(issue 34531)
connect-node was extracted from the core to CLI.
(issue 31417)
Jenkins.getInstance() returns null instance.
It was causing failures on Jenkins agents in the case of unexpected API usage by agents.
(issue 34857, regression in 2.4)
jenkins.model.Jenkins.disableExceptionOnNullInstance by
jenkins.model.Jenkins.enableExceptionOnNullInstance to address the
behavior change.
(issue 34857)
jenkins-ui (NPM module) is private, used only internally.
(issue 34629)
AbortExceptions.
(pull 2288)
hudson.model.UpdateCenter.defaultUpdateSiteId system property,
which allows specifying an alternate default Update Site ID.
(issue 34674)
context.xml and web.xml
in addition to setting system properties from the command line.
(issue 34755)
UpdateCenter by a custom implementation.
(issue 34733)
PluginManager by a custom implementation.
(issue 34681)
PeriodicWork if update site certificate is missing.
(issue 34745)
Downloadable items on restart if all update centers are up to date.
(issue 32886)
AbstractProject (e.g. Pipeline) jobs from CLI.
(issue 28071)
NoSuchMethodException in loginLink.jelly
when attempting to start a job using REST API.
(issue 31618)
ToolInstallers to follow HTTP 30x redirects.
(issue 23507)
NullPointerException in the parameter definition job property
if it gets initialized incorrectly.
(issue 34370)
Font Awesome and Google Fonts: Roboto dependencies
to prevent failures in the offline mode.
(issue 34628)
disconnect-node and reload-configuration were extracted from the core to CLI.
(issue 34328 and
issue 31900)
Jenkins.getInstance() to @Nonnull.
(new system property)
(pull 2297)
Older changelogs can be found in a separate file