This typically occurs when Tomcat runs out of it’s allocated memory (Heap size)
2023-02-09 12:37:21:132 UTC (Z) https-openssl-nio-443-exec-6 ERROR IntgServiceValidationFilter:112 - Exception in IntgServiceValidationFilter java.lang.OutOfMemoryError: Java heap space
2023-02-09 12:37:21:148 UTC (Z) https-openssl-nio-443-exec-10 ERROR AEBaseRestController:145 - Exception:
org.springframework.web.util.NestedServletException: Handler dispatch failed; nested exception is java.lang.OutOfMemoryError: Java heap space
This is the same memory that we allocate Tomcat to run on. After upgrading Tomcat, it should not be too low for our application and an active instance.
This could be considered as "one of the possible reasons“ for ‘Hazel instance not active’ error.