Extensions can't find

Hi,Everybody is good

I installed version 11.2, but I can’t find the extension.

Excuse me, what is the cause?
Thank you.
image

2019-04-01 17:43:12,521 [http://localhost:8080/bin/view/XWiki/Extensions?search=&repo=] ERROR o.x.e.r.i.RepositoryUtils      - Failed to search on repository [store.xwiki.com:xwiki:https://store.xwiki.com/xwiki/rest] with query [org.xwiki.extension.repository.search.ExtensionQuery@573e074e]. Ignore and go to next repository.
org.xwiki.extension.repository.search.SearchException: Failed to search extensions based on pattern []
        at org.xwiki.extension.repository.xwiki.internal.XWikiExtensionRepository.search(XWikiExtensionRepository.java:447)
        at org.xwiki.extension.repository.xwiki.internal.XWikiExtensionRepository.search(XWikiExtensionRepository.java:464)
        at org.xwiki.extension.repository.internal.RepositoryUtils.search(RepositoryUtils.java:468)
        at org.xwiki.extension.repository.internal.RepositoryUtils.search(RepositoryUtils.java:447)
        at org.xwiki.extension.repository.internal.RepositoryUtils.search(RepositoryUtils.java:409)
        at org.xwiki.extension.repository.internal.DefaultExtensionRepositoryManager.search(DefaultExtensionRepositoryManager.java:422)
        at org.xwiki.extension.repository.AbstractAdvancedSearchableExtensionRepository.search(AbstractAdvancedSearchableExtensionRepository.java:46)
        at org.xwiki.extension.script.ExtensionManagerScriptService.search(ExtensionManagerScriptService.java:190)
        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:497)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
        at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
        at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
        at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:567)
        at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:71)
        at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:142)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:87)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluateInternal(DefaultVelocityEngine.java:259)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:222)
        at com.xpn.xwiki.render.DefaultVelocityManager.evaluate(DefaultVelocityManager.java:358)
        at org.xwiki.rendering.internal.macro.velocity.VelocityMacro.evaluateString(VelocityMacro.java:131)
        at org.xwiki.rendering.internal.macro.velocity.VelocityMacro.evaluateString(VelocityMacro.java:52)
        at org.xwiki.rendering.macro.script.AbstractScriptMacro.evaluateBlock(AbstractScriptMacro.java:286)
        at org.xwiki.rendering.macro.script.AbstractScriptMacro.execute(AbstractScriptMacro.java:182)
        at org.xwiki.rendering.macro.script.AbstractScriptMacro.execute(AbstractScriptMacro.java:58)
        at org.xwiki.rendering.internal.transformation.macro.MacroTransformation.transform(MacroTransformation.java:297)
        at org.xwiki.rendering.internal.transformation.DefaultRenderingContext.transformInContext(DefaultRenderingContext.java:183)
        at org.xwiki.rendering.internal.transformation.DefaultTransformationManager.performTransformations(DefaultTransformationManager.java:101)
        at org.xwiki.display.internal.DocumentContentDisplayer.display(DocumentContentDisplayer.java:263)
        at org.xwiki.display.internal.DocumentContentDisplayer.display(DocumentContentDisplayer.java:133)
        at org.xwiki.display.internal.DocumentContentDisplayer.display(DocumentContentDisplayer.java:58)
        at org.xwiki.display.internal.DefaultDocumentDisplayer.display(DefaultDocumentDisplayer.java:96)
        at org.xwiki.display.internal.DefaultDocumentDisplayer.display(DefaultDocumentDisplayer.java:39)
        at org.xwiki.sheet.internal.SheetDocumentDisplayer.display(SheetDocumentDisplayer.java:123)
        at org.xwiki.sheet.internal.SheetDocumentDisplayer.display(SheetDocumentDisplayer.java:52)
        at org.xwiki.display.internal.ConfiguredDocumentDisplayer.display(ConfiguredDocumentDisplayer.java:68)
        at org.xwiki.display.internal.ConfiguredDocumentDisplayer.display(ConfiguredDocumentDisplayer.java:42)
        at com.xpn.xwiki.doc.XWikiDocument.display(XWikiDocument.java:1202)
        at com.xpn.xwiki.doc.XWikiDocument.getRenderedContent(XWikiDocument.java:1243)
        at com.xpn.xwiki.doc.XWikiDocument.getRenderedContent(XWikiDocument.java:1220)
        at com.xpn.xwiki.doc.XWikiDocument.getRenderedContent(XWikiDocument.java:1251)
        at com.xpn.xwiki.api.Document.getRenderedContent(Document.java:738)
        at sun.reflect.GeneratedMethodAccessor594.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
        at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
        at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
        at org.apache.velocity.runtime.parser.node.ASTReference.value(ASTReference.java:567)
        at org.apache.velocity.runtime.parser.node.ASTExpression.value(ASTExpression.java:71)
        at org.apache.velocity.runtime.parser.node.ASTSetDirective.render(ASTSetDirective.java:142)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.xwiki.velocity.introspection.TryCatchDirective.render(TryCatchDirective.java:87)
        at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluateInternal(DefaultVelocityEngine.java:259)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:222)
        at com.xpn.xwiki.render.DefaultVelocityManager.evaluate(DefaultVelocityManager.java:358)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.evaluateContent(InternalTemplateManager.java:847)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:723)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.lambda$renderFromSkin$0(InternalTemplateManager.java:698)
        at com.xpn.xwiki.internal.template.InternalTemplateManager$$Lambda$105/2020615620.call(Unknown Source)
        at com.xpn.xwiki.internal.security.authorization.DefaultAuthorExecutor.call(DefaultAuthorExecutor.java:98)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:697)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:676)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:662)
        at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:78)
        at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:2290)
        at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:2268)
        at com.xpn.xwiki.api.XWiki.parseTemplate(XWiki.java:992)
        at sun.reflect.GeneratedMethodAccessor267.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
        at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
        at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
        at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:369)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:216)
        at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:311)
        at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:230)
        at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluateInternal(DefaultVelocityEngine.java:259)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:222)
        at com.xpn.xwiki.render.DefaultVelocityManager.evaluate(DefaultVelocityManager.java:358)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.evaluateContent(InternalTemplateManager.java:847)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:723)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.lambda$renderFromSkin$0(InternalTemplateManager.java:698)
        at com.xpn.xwiki.internal.template.InternalTemplateManager$$Lambda$105/2020615620.call(Unknown Source)
        at com.xpn.xwiki.internal.security.authorization.DefaultAuthorExecutor.call(DefaultAuthorExecutor.java:98)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:697)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:676)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:662)
        at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:78)
        at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:2290)
        at com.xpn.xwiki.XWiki.parseTemplate(XWiki.java:2268)
        at com.xpn.xwiki.api.XWiki.parseTemplate(XWiki.java:992)
        at sun.reflect.GeneratedMethodAccessor267.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.doInvoke(UberspectImpl.java:395)
        at org.apache.velocity.util.introspection.UberspectImpl$VelMethodImpl.invoke(UberspectImpl.java:384)
        at org.apache.velocity.runtime.parser.node.ASTMethod.execute(ASTMethod.java:173)
        at org.apache.velocity.runtime.parser.node.ASTReference.execute(ASTReference.java:280)
        at org.apache.velocity.runtime.parser.node.ASTReference.render(ASTReference.java:369)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:216)
        at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:311)
        at org.apache.velocity.runtime.directive.RuntimeMacro.render(RuntimeMacro.java:230)
        at org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:207)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:87)
        at org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java:72)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java:106)
        at org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java:342)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluateInternal(DefaultVelocityEngine.java:259)
        at org.xwiki.velocity.internal.DefaultVelocityEngine.evaluate(DefaultVelocityEngine.java:222)
        at com.xpn.xwiki.render.DefaultVelocityManager.evaluate(DefaultVelocityManager.java:358)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.evaluateContent(InternalTemplateManager.java:847)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:723)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.lambda$renderFromSkin$0(InternalTemplateManager.java:698)
        at com.xpn.xwiki.internal.template.InternalTemplateManager$$Lambda$105/2020615620.call(Unknown Source)
        at com.xpn.xwiki.internal.security.authorization.DefaultAuthorExecutor.call(DefaultAuthorExecutor.java:98)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:697)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.renderFromSkin(InternalTemplateManager.java:676)
        at com.xpn.xwiki.internal.template.InternalTemplateManager.render(InternalTemplateManager.java:662)
        at com.xpn.xwiki.internal.template.DefaultTemplateManager.render(DefaultTemplateManager.java:78)
        at com.xpn.xwiki.XWiki.evaluateTemplate(XWiki.java:2290)
        at com.xpn.xwiki.web.Utils.parseTemplate(Utils.java:179)
        at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:489)
        at com.xpn.xwiki.web.XWikiAction.execute(XWikiAction.java:210)
        at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:425)
        at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:228)
        at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
        at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at com.xpn.xwiki.web.ActionFilter.doFilter(ActionFilter.java:112)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.wysiwyg.filter.ConversionFilter.doFilter(ConversionFilter.java:109)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.container.servlet.filters.internal.SetHTTPHeaderFilter.doFilter(SetHTTPHeaderFilter.java:63)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.container.servlet.filters.internal.SavedRequestRestorerFilter.doFilter(SavedRequestRestorerFilter.java:208)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.container.servlet.filters.internal.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:111)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.xwiki.resource.servlet.RoutingFilter.doFilter(RoutingFilter.java:132)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:198)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
        at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:650)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468)
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: Failed to request [https://store.xwiki.com/xwiki/rest/repository/search?start=0&number=20&q=]
        at org.xwiki.extension.repository.xwiki.internal.XWikiExtensionRepository.getRESTResource(XWikiExtensionRepository.java:247)
        at org.xwiki.extension.repository.xwiki.internal.XWikiExtensionRepository.getRESTObject(XWikiExtensionRepository.java:305)
        at org.xwiki.extension.repository.xwiki.internal.XWikiExtensionRepository.search(XWikiExtensionRepository.java:445)
        ... 194 common frames omitted
Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
        at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1937)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:302)
        at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:296)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1478)
        at sun.security.ssl.ClientHandshaker.processMessage(ClientHandshaker.java:212)
        at sun.security.ssl.Handshaker.processLoop(Handshaker.java:979)
        at sun.security.ssl.Handshaker.process_record(Handshaker.java:914)
        at sun.security.ssl.SSLSocketImpl.readRecord(SSLSocketImpl.java:1050)
        at sun.security.ssl.SSLSocketImpl.performInitialHandshake(SSLSocketImpl.java:1363)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1391)
        at sun.security.ssl.SSLSocketImpl.startHandshake(SSLSocketImpl.java:1375)
        at org.apache.http.conn.ssl.SSLConnectionSocketFactory.createLayeredSocket(SSLConnectionSocketFactory.java:396)
        at org.apache.http.conn.ssl.SSLConnectionSocketFactory.connectSocket(SSLConnectionSocketFactory.java:355)
        at org.apache.http.impl.conn.DefaultHttpClientConnectionOperator.connect(DefaultHttpClientConnectionOperator.java:142)
        at org.apache.http.impl.conn.PoolingHttpClientConnectionManager.connect(PoolingHttpClientConnectionManager.java:373)
        at org.apache.http.impl.execchain.MainClientExec.establishRoute(MainClientExec.java:394)
        at org.apache.http.impl.execchain.MainClientExec.execute(MainClientExec.java:237)
        at org.apache.http.impl.execchain.ProtocolExec.execute(ProtocolExec.java:185)
        at org.apache.http.impl.execchain.RetryExec.execute(RetryExec.java:89)
        at org.apache.http.impl.execchain.RedirectExec.execute(RedirectExec.java:110)
        at org.apache.http.impl.client.InternalHttpClient.doExecute(InternalHttpClient.java:185)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:83)
        at org.apache.http.impl.client.CloseableHttpClient.execute(CloseableHttpClient.java:108)
        at org.xwiki.extension.repository.xwiki.internal.XWikiExtensionRepository.getRESTResource(XWikiExtensionRepository.java:244)
        ... 196 common frames omitted
Caused by: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:387)
        at sun.security.validator.PKIXValidator.engineValidate(PKIXValidator.java:230)
        at sun.security.validator.Validator.validate(Validator.java:260)
        at sun.security.ssl.X509TrustManagerImpl.validate(X509TrustManagerImpl.java:324)
        at sun.security.ssl.X509TrustManagerImpl.checkTrusted(X509TrustManagerImpl.java:229)
        at sun.security.ssl.X509TrustManagerImpl.checkServerTrusted(X509TrustManagerImpl.java:124)
        at sun.security.ssl.ClientHandshaker.serverCertificate(ClientHandshaker.java:1460)
        ... 216 common frames omitted
Caused by: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
        at sun.security.provider.certpath.SunCertPathBuilder.build(SunCertPathBuilder.java:145)
        at sun.security.provider.certpath.SunCertPathBuilder.engineBuild(SunCertPathBuilder.java:131)
        at java.security.cert.CertPathBuilder.build(CertPathBuilder.java:280)
        at sun.security.validator.PKIXValidator.doBuild(PKIXValidator.java:382)
        ... 222 common frames omitted

Which version of Java are you using ? This error suggest that Let’s Encrypt certificate is not supported which was the case before Java 1.8.0_101.

I am using java version 1.8.0_45, should I upgrade the java version?
image

Definitely (but stay on Java 8_*). 1.8.0_45 is 5 years old.

In general Java minor versions should always be upgraded ASAP since they mostly contains critical bug and security fixes (which include trusted SSL certificate upgrades).

I upgraded the java version to jdk1.8.0_201 and the problem was solved.

thank you

hi,I found that I can’t find the extension of Markdown Syntax 1.2.

Yes, the extension index was not in a great shape. It’s being recreated, should be available soon.