We use GitHub Apps and yesterday everything worked fine. Today we get the following error message and are not able to do anything anymore.

Couldn't authenticate with GitHub app ID 115

org.kohsuke.github.HttpException: {"message":"'Issued at' claim ('iat') must be an Integer representing the time that the assertion was issued","documentation_url":"https://docs.github.com/enterprise/3.4/rest"}
at org.kohsuke.github.GitHubConnectorResponseErrorHandler$1.onError(GitHubConnectorResponseErrorHandler.java:56)
at org.kohsuke.github.GitHubClient.detectKnownErrors(GitHubClient.java:424)
at org.kohsuke.github.GitHubClient.sendRequest(GitHubClient.java:386)
at org.kohsuke.github.GitHubClient.sendRequest(GitHubClient.java:355)
at org.kohsuke.github.Requester.fetch(Requester.java:76)
at org.kohsuke.github.GitHub.getApp(GitHub.java:1160)
at org.jenkinsci.plugins.github_branch_source.GitHubAppCredentials.generateAppInstallationToken(GitHubAppCredentials.java:204)
Caused: java.lang.IllegalArgumentException: Couldn't authenticate with GitHub app ID 115
at org.jenkinsci.plugins.github_branch_source.GitHubAppCredentials.generateAppInstallationToken(GitHubAppCredentials.java:207)
at org.jenkinsci.plugins.github_branch_source.GitHubAppCredentials.getToken(GitHubAppCredentials.java:274)
at org.jenkinsci.plugins.github_branch_source.GitHubAppCredentials.access$300(GitHubAppCredentials.java:45)
at org.jenkinsci.plugins.github_branch_source.GitHubAppCredentials$CredentialsTokenProvider.getEncodedAuthorization(GitHubAppCredentials.java:184)
at org.kohsuke.github.GitHubClient.getEncodedAuthorization(GitHubClient.java:217)
at org.kohsuke.github.GitHubClient.prepareConnectorRequest(GitHubClient.java:446)
at org.kohsuke.github.GitHubClient.sendRequest(GitHubClient.java:377)
at org.kohsuke.github.GitHubClient.fetch(GitHubClient.java:121)
at org.kohsuke.github.GitHubClient.checkApiUrlValidity(GitHubClient.java:323)
at org.kohsuke.github.GitHub.checkApiUrlValidity(GitHub.java:1244)
at org.jenkinsci.plugins.github_branch_source.ApiRateLimitChecker.verifyConnection(ApiRateLimitChecker.java:197)
at org.jenkinsci.plugins.github_branch_source.Connector$GitHubConnection.verifyConnection(Connector.java:735)
at org.jenkinsci.plugins.github_branch_source.Connector.connect(Connector.java:397)
at org.jenkinsci.plugins.github_branch_source.GitHubAppCredentials$DescriptorImpl.doTestConnection(GitHubAppCredentials.java:660)
at java.base/java.lang.invoke.MethodHandle.invokeWithArguments(MethodHandle.java:710)
at org.kohsuke.stapler.Function$MethodFunction.invoke(Function.java:398)
at org.kohsuke.stapler.Function$InstanceFunction.invoke(Function.java:410)
at org.kohsuke.stapler.Function.bindAndInvoke(Function.java:208)
at org.kohsuke.stapler.SelectionInterceptedFunction$Adapter.invoke(SelectionInterceptedFunction.java:36)
at org.kohsuke.stapler.verb.HttpVerbInterceptor.invoke(HttpVerbInterceptor.java:48)
at org.kohsuke.stapler.SelectionInterceptedFunction.bindAndInvoke(SelectionInterceptedFunction.java:26)
at org.kohsuke.stapler.Function.bindAndInvokeAndServeResponse(Function.java:141)
at org.kohsuke.stapler.MetaClass$11.doDispatch(MetaClass.java:558)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:59)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:766)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:898)
at org.kohsuke.stapler.MetaClass$4.doDispatch(MetaClass.java:289)
at org.kohsuke.stapler.NameBasedDispatcher.dispatch(NameBasedDispatcher.java:59)
at org.kohsuke.stapler.Stapler.tryInvoke(Stapler.java:766)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:898)
at org.kohsuke.stapler.Stapler.invoke(Stapler.java:694)
at org.kohsuke.stapler.Stapler.service(Stapler.java:240)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799)
at org.eclipse.jetty.servlet.ServletHandler$ChainEnd.doFilter(ServletHandler.java:1626)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:157)
at jenkins.telemetry.impl.UserLanguages$AcceptLanguageFilter.doFilter(UserLanguages.java:129)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:154)
at jenkins.security.ResourceDomainFilter.doFilter(ResourceDomainFilter.java:81)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:154)
at hudson.plugins.greenballs.GreenBallFilter.doFilter(GreenBallFilter.java:64)
at hudson.util.PluginServletFilter$1.doFilter(PluginServletFilter.java:154)
at hudson.util.PluginServletFilter.doFilter(PluginServletFilter.java:160)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at hudson.security.csrf.CrumbFilter.doFilter(CrumbFilter.java:154)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:94)
at jenkins.security.AcegiSecurityExceptionFilter.doFilter(AcegiSecurityExceptionFilter.java:52)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at hudson.security.UnwrapSecurityExceptionFilter.doFilter(UnwrapSecurityExceptionFilter.java:54)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:122)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:116)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:109)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:102)
at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:93)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:219)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:213)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at jenkins.security.BasicHeaderProcessor.doFilter(BasicHeaderProcessor.java:97)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:110)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:80)
at hudson.security.HttpSessionContextIntegrationFilter2.doFilter(HttpSessionContextIntegrationFilter2.java:63)
at hudson.security.ChainedServletFilter$1.doFilter(ChainedServletFilter.java:99)
at hudson.security.ChainedServletFilter.doFilter(ChainedServletFilter.java:111)
at hudson.security.HudsonFilter.doFilter(HudsonFilter.java:172)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at org.kohsuke.stapler.compression.CompressionFilter.doFilter(CompressionFilter.java:53)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at hudson.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:86)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at org.kohsuke.stapler.DiagnosticThreadNameFilter.doFilter(DiagnosticThreadNameFilter.java:30)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at jenkins.security.SuspiciousRequestFilter.doFilter(SuspiciousRequestFilter.java:38)
at org.eclipse.jetty.servlet.FilterHolder.doFilter(FilterHolder.java:193)
at org.eclipse.jetty.servlet.ServletHandler$Chain.doFilter(ServletHandler.java:1601)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:548)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:578)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235)
at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624)
at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233)
at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1434)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:501)
at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186)
at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1349)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.HandlerList.handle(HandlerList.java:59)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
at org.eclipse.jetty.server.Server.handle(Server.java:516)
at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:388)
at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:633)
at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:380)
at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277)
at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105)
at org.eclipse.jetty.io.ssl.SslConnection$DecryptedEndPoint.onFillable(SslConnection.java:555)
at org.eclipse.jetty.io.ssl.SslConnection.onFillable(SslConnection.java:410)
at org.eclipse.jetty.io.ssl.SslConnection$2.succeeded(SslConnection.java:164)
at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105)
at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:338)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:315)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:173)
at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:131)
at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:386)
at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883)
at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034)
at java.base/java.lang.Thread.run(Thread.java:829)