What can I do to fix Resource is unhealthy and shouldn't be accessed for Exchange 365?

Question

I have been trying to get a new MRM policy to apply for an Exchange Online user, but have been failing over a 4 day period with the same error message.

The user has an Archive mailbox enabled, and the policy was newly created to permanently delete all items in "Deleted Items" folder over 60 days in age.

Ran in Exchange Online PowerShell:

$MRMLogs = [xml] ((Export-MailboxDiagnosticLogs <username> -ExtendedProperties).mailboxlog)
$MRMLogs.Properties.MailboxTable.Property | ? {$_.Name -like “*ELC*”}

This returned (truncated):

Name                                           Value                                                            
----                                           -----                                                            
ElcAssistantLock                               0                                                                
ElcFaiDeleteStatus                             DeleteNotAttempted                                               
ElcFaiSaveStatus                               SaveSucceeded                                                    
ElcLastRunSubAssistantProcessingTime           66844                                                            
ElcLastRunTotalProcessingTime                  70442                                                            
ELCLastSuccessTimestamp                        3/3/2025 12:36:33 AM                                             
IsELCFullCrawlNeeded                           False                                                            

When running diagnostic logs as follows:

Export-MailboxDiagnosticLogs <username> -ComponentName MRM   

This returned:

MailboxLog  : 2/27/2025 1:55:43 AM;method:InvokeInternalAssistant;file:\_\sources\dev\MailboxAssistants\src\assi               stants\ELC\ELCAssistant.cs:1107                Exception:               Microsoft.Exchange.WorkloadManagement.ResourceUnhealthyException: Resource               'DiskLatency(Guid:9b57e362-eab8-4592-887f-620f9886528d Name:NAMPR14DG264-db119               Volume:\\?\Volume{51a2edae-0d39-46ff-ba58-5ccc12c28ff3}\)' is unhealthy and shouldn't be accessed.                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCHealthMonitor.InternalThrottleStoreCa               ll(List`1 archiveResourceDependencies)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcSubAssistant.ThrottleStoreCallAndChec               kForShutdown(IExchangePrincipal mailboxOwner, List`1 archiveResourceDependencies)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ItemPropertySynchronizer.<>c__DisplayCla               ss36_0.<CommitChangesAlready>b__0()                  at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2               filterDelegate, Action`1 catchDelegate)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ItemPropertySynchronizer.Update()                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.FolderPropertySynchronizer.Update()                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.Synchronizer.ProcessFolder(List`1               folderList)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.Synchronizer.UpdateEntireMailbox()                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.TagProvisioner.InvokeInternal(MailboxDat               aForTags mailboxDataForTags, IAnalyticsClient analyticsClient)                  at               Microsoft.Exchange.MailboxAssistants.Assistants.ELC.TagProvisioner.Invoke(MailboxDataForTags               mailboxDataForTags, IAnalyticsClient analyticsClient)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcTagSubAssistant.InvokeInternal(IStore               Session mailboxSession, MailboxDataForTags mailboxDataForTags, IAnalyticsClient analyticsClient)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcTagSubAssistant.Invoke(IStoreSession               mailboxSession, MailboxDataForTags mailboxDataForTags, IAnalyticsClient analyticsClient)                  at               Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCAssistant.InvokeCore(IElcInvokeContext               context, List`1 customDataToLog, StatisticsLogEntry logEntry, ElcParameters parameters,               IElcAssistantSnapshot snapshot, IAnalyticsClient elcAnalytics)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCAssistant.<>c__DisplayClass31_0.<Invo               keInternalAssistant>b__1()                  at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2               filterDelegate, Action`1 catchDelegate)                2/27/2025 1:54:23 AM;method:InvokeInternalAssistant;file:\_\sources\dev\MailboxAssistants\src\assi               stants\ELC\ELCAssistant.cs:1107                Exception:               Microsoft.Exchange.WorkloadManagement.ResourceUnhealthyException: Resource               'DiskLatency(Guid:9b57e362-eab8-4592-887f-620f9886528d Name:NAMPR14DG264-db119               Volume:\\?\Volume{51a2edae-0d39-46ff-ba58-5ccc12c28ff3}\)' is unhealthy and shouldn't be accessed.                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCHealthMonitor.InternalThrottleStoreCa               ll(List`1 archiveResourceDependencies)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcSubAssistant.ThrottleStoreCallAndChec               kForShutdown(IExchangePrincipal mailboxOwner, List`1 archiveResourceDependencies)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ItemPropertySynchronizer.<>c__DisplayCla               ss36_0.<CommitChangesAlready>b__0()                  at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2               filterDelegate, Action`1 catchDelegate)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ItemPropertySynchronizer.Update()                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.FolderPropertySynchronizer.Update()                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.Synchronizer.ProcessFolder(List`1               folderList)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.Synchronizer.UpdateEntireMailbox()                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.TagProvisioner.InvokeInternal(MailboxDat               aForTags mailboxDataForTags, IAnalyticsClient analyticsClient)                  at               Microsoft.Exchange.MailboxAssistants.Assistants.ELC.TagProvisioner.Invoke(MailboxDataForTags               mailboxDataForTags, IAnalyticsClient analyticsClient)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcTagSubAssistant.InvokeInternal(IStore               Session mailboxSession, MailboxDataForTags mailboxDataForTags, IAnalyticsClient analyticsClient)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ElcTagSubAssistant.Invoke(IStoreSession               mailboxSession, MailboxDataForTags mailboxDataForTags, IAnalyticsClient analyticsClient)                  at               Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCAssistant.InvokeCore(IElcInvokeContext               context, List`1 customDataToLog, StatisticsLogEntry logEntry, ElcParameters parameters,               IElcAssistantSnapshot snapshot, IAnalyticsClient elcAnalytics)                  at Microsoft.Exchange.MailboxAssistants.Assistants.ELC.ELCAssistant.<>c__DisplayClass31_0.<Invo               keInternalAssistant>b__1()                  at Microsoft.Exchange.Common.IL.ILUtil.DoTryFilterCatch(Action tryDelegate, Func`2               filterDelegate, Action`1 catchDelegate)   

LogName     : MRM 
Identity    : username 
IsValid     : True 
ObjectState : Unchanged 

Error is:

Microsoft.Exchange.WorkloadManagement.ResourceUnhealthyException: Resource
              'DiskLatency(Guid:9b57e362-eab8-4592-887f-620f9886528d Name:NAMPR14DG264-db119
              Volume:\\?\Volume{51a2edae-0d39-46ff-ba58-5ccc12c28ff3}\)' is unhealthy and shouldn't be accessed.

Answer 1

Hello, @Aaron Johnson

Welcome to the Microsoft Q&A platform!

The error comes from Exchange Online’s backend storage subsystem. The MRM (Messaging Records Management) process is trying to access a disk resource that Exchange has flagged as unhealthy because it’s showing high latency or other performance issues. This isn’t usually an issue with your MRM policy configuration or your mailbox settings—it means that the backend infrastructure (the disk hosting that part of the mailbox or archive) is experiencing problems, and the system is preventing access to protect data and performance.

What you can do on your side is as follows below:

1.Confirm that nothing in your configuration is causing problems. In your case the policy is new and the error points strongly toward a resource issue, so the configuration isn’t likely to be the source.

2.Try running the process again after waiting a bit. These “unhealthy” errors can sometimes be transient.  

3.Check for any known service issues via the Microsoft 365 Service Health Dashboard. If there’s an ongoing infrastructure issue in your region or tenant, it might be affecting operations.

If the error persists, since you’re working in Exchange Online, the underlying disk and its health aren’t under your direct control. If the error continues even after waiting (and you’ve verified no configuration errors on your end), the next step is to raise a support ticket with Microsoft 365 Support. When opening the case, include details such as the full error message, the log excerpts you provided, the specific disk identifier from the error message, and a description of the troubleshooting you’ve already attempted. This will help Microsoft’s support team diagnose whether there’s a broader issue with the infrastructure that they need to address.

Should you need more help on this, you can feel free to post back. 

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If the answer is helpful, please click on “Accept answer” as it could help other members of the Microsoft Q&A community who have similar questions and are looking for solutions.

Thank you for your support and understanding.

Best Wishes,

Alex Zhang