DRS status page is blank for cluster in ACS 4.20.2.0

[GerorgeEG]

problem

We have DRS enabled for cluster and it is also migrating the VM's as per the set configuration. But when we got to DRS tab in the cluster settings , its status page is showing blanked. Below is the screenshot

Logs in management server when we are trying to get the details

2026-06-19 12:54:08,481 ERROR [c.c.a.ApiServer] (qtp253011924-8461:[ctx-aaf556dd, ctx-bdf2c1bf]) (logid:eb42248f) unhandled exception executing api command: [Ljava.lang.String;@284b219 java.lang.NullPointerException: Cannot invoke "com.cloud.event.EventVO.getUuid()" because "event" is null
at org.apache.cloudstack.cluster.ClusterDrsServiceImpl.listDrsPlan(ClusterDrsServiceImpl.java:836)
at org.apache.cloudstack.api.command.admin.cluster.ListClusterDrsPlanCmd.execute(ListClusterDrsPlanCmd.java:57)
at com.cloud.api.ApiDispatcher.dispatch(ApiDispatcher.java:173)
at com.cloud.api.ApiServer.queueCommand(ApiServer.java:830)
at com.cloud.api.ApiServer.handleRequest(ApiServer.java:654)
at com.cloud.api.ApiServlet.processRequestInContext(ApiServlet.java:351)
at com.cloud.api.ApiServlet$1.run(ApiServlet.java:154)
at org.apache.cloudstack.managed.context.impl.DefaultManagedContext$1.call(DefaultManagedContext.java:56)
at org.apache.cloudstack.managed.context.impl.DefaultManagedContext.callWithContext(DefaultManagedContext.java:103)
at org.apache.cloudstack.managed.context.impl.DefaultManagedContext.runWithContext(DefaultManagedContext.java:53)
at com.cloud.api.ApiServlet.processRequest(ApiServlet.java:151)
at com.cloud.api.ApiServlet.doGet(ApiServlet.java:105)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:645)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:750)
at org.eclipse.jetty.servlet.ServletHolder$NotAsync.service(ServletHolder.java:1450)
at org.eclipse.jetty.servlet.ServletHolder.handle(ServletHolder.java:799)
at org.eclipse.jetty.servlet.ServletHandler.doHandle(ServletHandler.java:554)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143)
at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:600)
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:1440)
at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188)
at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:505)
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:1355)
at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141)
at org.eclipse.jetty.server.handler.gzip.GzipHandler.handle(GzipHandler.java:772)
at org.eclipse.jetty.server.handler.HandlerCollection.handle(HandlerCollection.java:146)
at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127)
at org.eclipse.jetty.server.Server.handle(Server.java:516)

versions

ACS Version: 4.20.2.0
DB : Maria DB 10.3.39
ACS and KVM host : RHEL 8

The steps to reproduce the bug

1. Go to Cluster --> DRS tab
2. When try with api getting below error

list clusterdrsplan
🙈 Error: (HTTP 530, error code 9999) Cannot invoke "com.cloud.event.EventVO.getUuid()" because "event" is null
(acs-ams-swis) 🐱 > list clusterdrsplan clusterid=5501e4b4-2599-4f31-981a-130c28c61bab
🙈 Error: (HTTP 530, error code 9999) Cannot invoke "com.cloud.event.EventVO.getUuid()" because "event" is null
3.
...

What to do about it?

No response

[vishesh92]

@GerorgeEG Just a hunch. We clear older events and DRS Plan also uses events. This seems to be resulting in making it unusable because of the null pointer exception. What is the value for event.purge.delay & drs.plan.expire.interval?