We are seeing an issue where the managed servers are going into an null state ( all the runtime information about the managed servers is not available) , however the managed servers are up and running and are processing the requests from the user. All the manged server are showing up but for one its showing no state.
In this kind of issue usual solution is to do a clean bounce of the domain including admin server, clearing cache and tmp. If that does not work then check for below configurations.
Invocation Timeout Seconds :
The number of seconds that internal WebLogic Server processes wait to connect to an MBean server, invoke an MBean server method, and return the results of the invocation. If the MBean server method does not complete (return) within the timeout period, WebLogic Server abandons its invocation attempt.
Some internal management processes within WebLogic Server require a server instance to connect to MBean servers in other WebLogic Server instances and invoke an MBean server method. The timeout period prevents the internal process from locking up if an MBean server cannot successfully return a method invocation.
A value of 0 (zero) prevents the method invocation from timing out. With such a value, the internal process will wait indefinitely until the MBean server’s method returns.
Minimum value: 0
Maximum value: 2147483647
Login to Console – Click on Domain Name on left panel -> Configuration -> General, Advanced tab. Change “Invocation Timeout Seconds:” value to “0” seconds from default 30 seconds.See below screenshot.
once changed save the configuration and activate the changes and bounce the domain and check. That should resolve the issue.