The are a lot of passivation exceptions happening occationally in Production. I see a lot of posts talking about the hotfixes from Pega side. But we are using Pega 8.1 version.

Below are some details of exception:

[ES PassivationDaemon] [ STANDARD] [ ] [ ] ( mgmt.base.NodeRequestorMgt) ERROR - One or more properties could not be serialized during passivation and have therefore been lost. They will not be available on activation. Please ensure that all property data is Serializable;com.pega.pegarules.session.external.mgmt.PageCannotBeSerializedForPassivationException: Unable to passivate page 'pyTempDisplayParamPage' on thread 'STANDARD' in requestor ''. The following items were not serializable: [Property not serializable: "pyTempDisplayParamPage.CDSystemUserRecents" Class: "com.pega.pegarules.data.internal.dictionary.ClassDefinitionImpl"