Ops Manager error: "There was a problem fetching your clusters"

Hello,

Our Ops Manager stopped working, it shows the error “There was a problem fetching your clusters.” on the front page. Also, the Kubernetes pod/ops-manager-0 shows more details:

2021-02-23T07:51:06.315+0000 [JettyHttpPool-324] ERROR com.xgen.svc.mms.res.exception.DefaultThrowableHandler [DefaultThrowableHandler.java.handle:33] - com.xgen.svc.mms.res.AllClustersResource.getAllClustersForUser(javax.servlet.http.HttpServletRequest) - msg: null
java.lang.NullPointerException: null
        at com.xgen.svc.mms.res.view.allclusters.OrgGroupView$OrgGroupViewComparator.compare(OrgGroupView.java:127)
        at com.xgen.svc.mms.res.view.allclusters.OrgGroupView$OrgGroupViewComparator.compare(OrgGroupView.java:101)
        at java.base/java.util.TimSort.countRunAndMakeAscending(TimSort.java:355)
        at java.base/java.util.TimSort.sort(TimSort.java:220)
        at java.base/java.util.Arrays.sort(Arrays.java:1515)
        at java.base/java.util.stream.SortedOps$SizedRefSortingSink.end(SortedOps.java:353)
        at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:485)
        at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474)
        at java.base/java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:913)
        at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
        at java.base/java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:578)
        at com.xgen.svc.mms.res.AllClustersResource.generateGroupViews(AllClustersResource.java:101)
        at com.xgen.svc.mms.res.AllClustersResource.getAllClusters(AllClustersResource.java:75)
        at com.xgen.svc.mms.res.AllClustersResource_$$_jvstfcf_10._d16getAllClusters(AllClustersResource_$$_jvstfcf_10.java)
        at jdk.internal.reflect.GeneratedMethodAccessor266.invoke(Unknown Source)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.glassfish.hk2.utilities.reflection.ReflectionHelper.invoke(ReflectionHelper.java:1287)
        at org.jvnet.hk2.internal.MethodInterceptorHandler.invoke(MethodInterceptorHandler.java:103)
        at com.xgen.svc.mms.res.AllClustersResource_$$_jvstfcf_10.getAllClusters(AllClustersResource_$$_jvstfcf_10.java)
        at com.xgen.svc.mms.res.AllClustersResource.getAllClustersForUser(AllClustersResource.java:50)
        at com.xgen.svc.mms.res.AllClustersResource_$$_jvstfcf_10._d18getAllClustersForUser(AllClustersResource_$$_jvstfcf_10.java)
        at jdk.internal.reflect.GeneratedMethodAccessor265.invoke(Unknown Source)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.glassfish.hk2.utilities.reflection.ReflectionHelper.invoke(ReflectionHelper.java:1287)
        at org.jvnet.hk2.internal.MethodInterceptorHandler$MethodInvocationImpl.proceed(MethodInterceptorHandler.java:188)
        at com.xgen.module.upgrademode.AppUpgradeModeInterceptor.invoke(AppUpgradeModeInterceptor.java:35)
        at org.jvnet.hk2.internal.MethodInterceptorHandler$MethodInvocationImpl.proceed(MethodInterceptorHandler.java:211)
        at com.xgen.svc.mms.util.MethodCallStatsDImpl.invoke(MethodCallStatsDImpl.java:25)
        at org.jvnet.hk2.internal.MethodInterceptorHandler.invoke(MethodInterceptorHandler.java:121)
        at com.xgen.svc.mms.res.AllClustersResource_$$_jvstfcf_10.getAllClustersForUser(AllClustersResource_$$_jvstfcf_10.java)
        at jdk.internal.reflect.GeneratedMethodAccessor264.invoke(Unknown Source)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:566)
        at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.lambda$static$0(ResourceMethodInvocationHandlerFactory.java:76)
        at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:148)
        at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:191)
        at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:200)
        at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:103)
        at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:493)
        at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:415)
        at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:104)
        at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:277)
        at org.glassfish.jersey.internal.Errors$1.call(Errors.java:272)
        at org.glassfish.jersey.internal.Errors$1.call(Errors.java:268)
        at org.glassfish.jersey.internal.Errors.process(Errors.java:316)
        at org.glassfish.jersey.internal.Errors.process(Errors.java:298)
        at org.glassfish.jersey.internal.Errors.process(Errors.java:268)
        at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:289)
        at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:256)
        at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:703)
        at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:416)
        at org.glassfish.jersey.servlet.ServletContainer.serviceImpl(ServletContainer.java:409)
        at org.glassfish.jersey.servlet.ServletContainer.doFilter(ServletContainer.java:584)
        at org.glassfish.jersey.servlet.ServletContainer.doFilter(ServletContainer.java:525)
        at org.glassfish.jersey.servlet.ServletContainer.doFilter(ServletContainer.java:462)
        at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:82)
        at com.xgen.svc.brs.slurp.IncorrectContentTypeFilter.doFilter(IncorrectContentTypeFilter.java:30)
        at com.google.inject.servlet.FilterChainInvocation.doFilter(FilterChainInvocation.java:82)
        at com.google.inject.servlet.ManagedFilterPipeline.dispatch(ManagedFilterPipeline.java:121)
        at com.google.inject.servlet.GuiceFilter.doFilter(GuiceFilter.java:133)
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1610)
        at com.xgen.svc.mms.res.filter.GzipDecompressFilter.doFilter(GzipDecompressFilter.java:49)
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1610)
        at org.eclipse.jetty.servlets.GzipFilter.doFilter(GzipFilter.java:51)
        at org.eclipse.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1610)
        at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:540)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:146)
        at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:753)
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:548)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:257)
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1700)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:255)
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1345)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:203)
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:480)
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1667)
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:201)
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1247)
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:144)
        at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:152)
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:132)
        at org.eclipse.jetty.server.Server.handle(Server.java:505)
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:370)
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:267)
        at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:305)
        at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:103)
        at org.eclipse.jetty.io.ChannelEndPoint$2.run(ChannelEndPoint.java:117)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.runTask(EatWhatYouKill.java:333)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.doProduce(EatWhatYouKill.java:310)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.tryProduce(EatWhatYouKill.java:168)
        at org.eclipse.jetty.util.thread.strategy.EatWhatYouKill.run(EatWhatYouKill.java:126)
        at org.eclipse.jetty.util.thread.ReservedThreadExecutor$ReservedThread.run(ReservedThreadExecutor.java:366)
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:698)
        at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:804)
        at java.base/java.lang.Thread.run(Thread.java:834)

The rest of links work fine and all the clusters are available via UserAccount > Organizations string. The clusters with replica sets work as well.

If someone has some ideas or suggestions about this issue, please share your thoughts.
Thank you.