Fix StalledDuetoMRS_Quarantined Error in Exchange Migrations

Has your StalledDuetoMRS_Quarantined put a break on your Exchange migration?

This happens when your Exchange Server detects a possible error in the database undergoing transfer automatically pauses the act from happening. This may seem like an error but is actually a safety precaution built it to cutoff corrupt database  from effecting rest of the systems.

Don’t’ worry by reading this writeup you can learn why it happens and stop it from happening with a range of different solutions.

Why You May See StalledDueToMRS_Quarantined Error during Exchange Server Migrations?

• The Exchange Server is still running a faulty instance.
• Mailbox Replication Service (MRS) Proxy is Off.
• User Mailboxes are Cluttered or in an Unclean State.
• If you believe Mailboxes are Corrupt then repair corrupt Exchange database and restart.
• Resource Conflict Between Workload Management and MRS.

Also Read: Export Gmail Emails to MBOX in Google Workspace Business

There are the most common reasons so we will address them one by one starting with the faulty instance.

Upgrade to A Stable Exchange Version & Fix StalledDuetoMRS_Quarantined Error

If you are using Exchange Server 2019 CU 12 or older then you may see the StalledDuetoMRS_Quarantined error when you attempt a public folder mailbox migration.

The full error message resembles the message admins see during a mailbox export stalled due to source disk latency error and is as follows:

StatusDetail: StalledDueToMRS_Quarantined

Message: Request was quarantined because of following error: Object of type "Microsoft.Exchange.Data.Storage.PublicFolderSession" cannot be converted to object of type "Microsoft.Exchange.Data.Storage.MailboxSession".

There is a simple fix to this simply install and update to Cumulative Update 13 or later version of Exchange Server 2019.

Prevent  StalledDuetoMRS_Quarantined Alerts By Enabling Proxy

Microsoft explicitly states that MRS with a proxy endpoint is mandatory for all non-local data movements. Which includes the ones that occur during Exchange Server Cross Forest Migration or Exchange On-Premise to Exchange Online Migration. So admins must enable the Mailbox Replication Service’s proxy endpoint function.

You can get a rough idea about the procedure in the following steps

• In EAC visit Servers > Virtual Directories.
• Filter for the EWS virtual directory you want to configure and select it.
• Click Edit (pencil Icon).
• On the General tab, select Enable MRS Proxy endpoint & Save.

You can also use the PowerShell cmdlet whose syntax is as follows

Set-WebServicesVirtualDirectory -Identity “[<Server>\]EWS (Default Web Site)” -MRSProxyEnabled $true

Edit the variables as per your need. If you still see the error after this then move on to the next solution.

Tidy the To-be Migrated Mailboxes

Unclean mailboxes put the server under unnecessary load. With Migration itself being such a resource-intensive task any other non-optimized part may trigger a quarantine protocol for safety reasons.

That is why it is important that admins conduct we will use two inbuilt cleanup mechanisms to quickly rid the mailboxes of redundant data. Like done for fixing the stalled due to target processor error in Exchange Server migrations.

Before using these please ensure you have Outlook desktop client installed and set up.

Once done proceed with the following.

Open the run module and put in.

1. Outlook.exe /cleanviews wait for the process to complete then.
2. In a new run module instance type Outlook.exe /cleanfinders.

After this retry the move request and see if the StalledDueToMRS_Quarantined error pops up or not. If the dirty mailbox was the reason for the error, should no longer appear and you will be able to continue the migration as usual. If not then apply the next remedy.

Disable the Quarantine Option for the Exchange Server Mailbox

A mailbox under quarantine will stall the migration midway. That is why admins need to disable this feature. Fortunately, a simple PowerShell cmdlet will do the trick.

Open EMS or connect regular PowerShell with your Exchange server.

Type Disable-MailboxQuarantine –Identity <mailbox identity>

and Press Enter.

As this is a security mechanism Exchange Server will throw a confirmation request.

Press the Y or A key on and continue.

This will prevent your mailbox from going under quarantine. You can confirm by via another PowerShell command:

Get-MailboxStatistics <mailbox_identifier> | Select DisplayName, IsQuarantined | Format-Table

The IsQuarantined flag should be False.

Getting StalledDueToMRS_Quarantined When Moving Mailboxes from EXH2016 to EXH2010

In case you are someone who has to do a reverse migration (i.e. a downgrade from a 2019 version to 2013 or 2016 to 2010) then you can bypass the error first.
Exporting Exchange Server Mailboxes to PST.

Then, disable the original mailbox on the 2016 server.

At last build equivalent, mailboxes on the 2010 Server and use the native import mechanism to add the PST.

This export-import is the only valid choice if you are looking for a native downgrade migration solution.

Conclusion

Admins now have the toolkit to end a StalledDuetoMRS_Quarantined error during Exchange Server migrations. Errors like this one significantly extend the planned downtime during a migration. So it is better to use an alternative automated migration solution like the SysTools Exchange to Office Migration Tool.  A sister variant of the tool designed for pure Exchange to Exchange transfer can perform Exchange Server migration from a higher edition source to a lower edition destination without any additional effort.

Frequently Asked Questions

• Q. If the Mailbox are kept in quarantine because of StalledDuetoMRS_Quarantined error then how do any of the repair techniques work?
  A. That is because StalledDuetoMRS_Quarantined error is in fact a flag. When your Exchange Server reads it and gets a positive signal then it pauses the migration. Your mailbox and its corresponding data can still be interacted with that is why all repair methods can still be used.
• Q. How long I leave server in a StalledDuetoMRS_Quarantined state ?
  Depends on your own requirement. Nothing is going to happen your data (unless its corrupt). The main issue is keeping the stall active beyond the recommended range prolongs the  downtime. So your users will experience delay in regular business operations.
• Q. What to do if I still see the error after performing Outlook.exe /cleanviews  & Outlook.exe /cleanfinders?
  A. If the Outlook level cleaning won’t fix your issue then that means there are problems with the underlying files themselves. Therefore you should perform an EDB repair to fix the problem.