Microsoft has released security updates (SUs) that resolve vulnerabilities found in:
Exchange Server 2013
Exchange Server 2016
Exchange Server 2019
IMPORTANT: When manually installing SUs...
Updated Mar 16, 2022
Version 6.0
Blog Post
The January SU broke eDiscovery in ECP on Exchange 2013 "Deserialization of type Microsoft.Exchange.Data.PropertyBag+ValuePair blocked due to NotInAllow at location MailboxDataStore."
I opened a support case and within a few days I got a response that it is a known issue and will be fixed in the next SU. Then support updated me that the fix was slated for the next CU. As we know, there are no more CUs planned for Exchange 2013. So the fix will be released...never?
It was really disappointing that it wasn't included in this CU, having been diagnosed and fixed weeks earlier. The work-around of using EMS for discovery doesn't work. It's the legal team that needs eDiscovery. They don't have access to EMS, nor would they want it.