StoreWorker fails because of BaseViewOperatorDefinition

Symptoms 

The StoreWorker process stops responding in Microsoft Exchange Server 2019 or 2016. When this issue occurs, the mailboxes get quarantined, and the following error entry is logged:

ProviderName : MSExchangeIS

Id           : 1002

Message      : Unhandled exception (System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.Exchange.Server.Storage.LogicalDataModel.SearchFolder.BaseViewOperatorDefinition(Context context, Mailbox mailbox, IList`1 columnsToFetch, SearchCriteria criteria, Nullable`1 associated)

Resolution

To fix this issue, install the following cumulative updates, as appropriate:

• For Exchange Server 2019, install:
  
  Hotfix update for Exchange Server 2019 CU15 HU2: May 29, 2025 (KB5057651) 
  
  Hotfix update for Exchange Server 2019 CU14 HU5: May 29, 2025 (KB5057652)

• For Exchange Server 2016, install:
  
  Hotfix update for Exchange Server 2016 CU23 HU16: May 29, 2025 (KB5057653)