Upgrading from 2.121.1 to 2.121.2 and it throws the error above.
hudson.util.HudsonFailedToLoad: org.jvnet.hudson.reactor.ReactorException: java.io.IOException: Unable to read /var/lib/jenkins/config.xml at hudson.WebAppMain$3.run(WebAppMain.java:244) Caused by: org.jvnet.hudson.reactor.ReactorException: java.io.IOException: Unable to read /var/lib/jenkins/config.xml at org.jvnet.hudson.reactor.Reactor.execute(Reactor.java:269) at jenkins.InitReactorRunner.run(InitReactorRunner.java:45) at jenkins.model.Jenkins.executeReactor(Jenkins.java:1010) at jenkins.model.Jenkins.<init>(Jenkins.java:878) at hudson.model.Hudson.<init>(Hudson.java:85) at hudson.model.Hudson.<init>(Hudson.java:81) at hudson.WebAppMain$3.run(WebAppMain.java:227) Caused by: java.io.IOException: Unable to read /var/lib/jenkins/config.xml at hudson.XmlFile.unmarshal(XmlFile.java:165) at jenkins.model.Jenkins.loadConfig(Jenkins.java:2786) at jenkins.model.Jenkins.access$700(Jenkins.java:325) at jenkins.model.Jenkins$16.run(Jenkins.java:2804) at org.jvnet.hudson.reactor.TaskGraphBuilder$TaskImpl.run(TaskGraphBuilder.java:169) at org.jvnet.hudson.reactor.Reactor.runTask(Reactor.java:282) at jenkins.model.Jenkins$7.runTask(Jenkins.java:999) at org.jvnet.hudson.reactor.Reactor$2.run(Reactor.java:210) at org.jvnet.hudson.reactor.Reactor$Node.run(Reactor.java:117) 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 by: com.thoughtworks.xstream.io.StreamException: : only 1.0 is supported as <?xml version not '1.1' (position: START_DOCUMENT seen <?xml version=\'1.1\'... @1:19) at com.thoughtworks.xstream.io.xml.XppReader.pullNextEvent(XppReader.java:124) at com.thoughtworks.xstream.io.xml.AbstractPullReader.readRealEvent(AbstractPullReader.java:148) at com.thoughtworks.xstream.io.xml.AbstractPullReader.readEvent(AbstractPullReader.java:141) at com.thoughtworks.xstream.io.xml.AbstractPullReader.move(AbstractPullReader.java:118) at com.thoughtworks.xstream.io.xml.AbstractPullReader.moveDown(AbstractPullReader.java:103) at com.thoughtworks.xstream.io.xml.XppReader.<init>(XppReader.java:63) at com.thoughtworks.xstream.io.xml.AbstractXppDriver.createReader(AbstractXppDriver.java:54) at com.thoughtworks.xstream.io.xml.AbstractXppDriver.createReader(AbstractXppDriver.java:65) at hudson.XmlFile.unmarshal(XmlFile.java:163) ... 11 more Caused by: org.xmlpull.v1.XmlPullParserException: only 1.0 is supported as <?xml version not '1.1' (position: START_DOCUMENT seen <?xml version=\'1.1\'... @1:19) at org.xmlpull.mxp1.MXParser.parseXmlDeclWithVersion(MXParser.java:2608) at org.xmlpull.mxp1.MXParser.parseXmlDecl(MXParser.java:2592) at org.xmlpull.mxp1.MXParser.parsePI(MXParser.java:2466) at org.xmlpull.mxp1.MXParser.parseProlog(MXParser.java:1447) at org.xmlpull.mxp1.MXParser.nextImpl(MXParser.java:1395) at org.xmlpull.mxp1.MXParser.next(MXParser.java:1093) at com.thoughtworks.xstream.io.xml.XppReader.pullNextEvent(XppReader.java:109) ... 19 more