MSExchange OWA, Event 146

I get below error often in Application log of Exchange Server (MSExchange OWA, Event 146). How could I solve this problem. I think that user was deleted in AD, while mailbox was not....

Thanks for help in advance!

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Outlook Web App failed to create ExchangePrincipal for S-1-5-21-3178225484-391519746-223417597-1730. IsMonitoringRequest: False. Error: Microsoft.Exchange.Data.Storage.AdUserNotFoundException: The Active Directory user wasn't found.

   at Microsoft.Exchange.Data.Storage.ExchangePrincipal..ctor(ADUser user, ADObjectId mdb, DatabaseLocationInfo databaseLocationInfo, RemotingOptions remotingOptions, Boolean asArchive, IPerformanceDataLogger performanceLogger)

   at Microsoft.Exchange.Data.Storage.ExchangePrincipal.InternalFromADUser(ADUser user, ADObjectId mdb, DatabaseLocationInfo databaseLocationInfo, RemotingOptions remotingOptions, Boolean asArchive, IPerformanceDataLogger performanceLogger)

   at Microsoft.Exchange.Data.Storage.ExchangePrincipal.InternalFromADUser(ADUser user, RemotingOptions remotingOptions, IPerformanceDataLogger performanceLogger)

   at Microsoft.Exchange.Data.Storage.ExchangePrincipal.FromUserSid(IRecipientSession recipientSession, SecurityIdentifier userSid, RemotingOptions remotingOptions)

   at Microsoft.Exchange.Clients.Owa2.Server.Core.OwaClientSecurityContextIdentity.InternalCreateExchangePrincipal()