Recently I observed this issue during the migration of Exchange 2010 to Exchange 2016. Following are the symptoms noticed not for all but for very few users (less than 1%).

1. Unable to do Deep search on Outlook Address Book (Cached mode), such as with phone number, department etc.
2. Unable to succeed “Test E-mail AutoConfiguration” test from Outlook
3. Availability information were not displaying
4. Outlook returns following error while configuring profile,
"An encrypted connection to your mail server is not available.
Click next to attempt using an unencrypted connection."

Outlook New Profile Error

And similar other symptoms which occurs due to inadequate autodiscover information.

Suspected Reason and Solution

As you may aware, the mailbox move disconnects the Exchange 2010 mailboxes and connects the Exchange 2016 mailbox during the “Completing” stage if migration/move process. Which means, following stale information are present in the infra,

1. Mailbox Move for each user in the Migration batch
2. Disconnected Mailboxes at Exchange 2010 infra

The issue happens (I assume) because of the incomplete replication of information, and possibly due to the conflicts between connected and disconnected mailboxes. The solution in my case was fairly simple,

1. Remove the “Completed” move request against the user
        2. Restart "MSExchangeAutodiscoverAppPool" WebappPool on all Exchange 2016 servers "Restart-WebAppPool MSExchangeAutodiscoverAppPool"
3. Wait for 10 – 20 minutes, and try to test the autodiscover

The above helped me to restore the services back for the user who impacted. Share your experience in the form of comments.




Since the introduction of DAG into Exchange Server architecture, the DR situations became more easy and comfortable to deal with. On this article I have tried to pen down a simple and straight forward process on how to deal with DR scenario.

My LAB Servers:

Exchange Servers (4 nos): EX16-01, EX16-02, EX16-03, EX16-Dr1

AD Servers: 2010adc1 & 2010adc2 (both work as Witness/Alternate Witness servers respectively)

DAG Name: DAG02 (Please note I have configured Exchange Server 2016 DAG without cluster object)

Witness Server Information:

WitnessServer             :

WitnessDirectory         : c:\DAG02

Alt Witness Server       :

Alt Witness Dir            : c:\DAG02

Scenario: 2 Servers in Primary Datacenter & 2 Servers in Secondary datacenter. I plan to bring down 2 servers EX16-02 & EX16-03 and restore the DAG with EX16-01 & EX16-dr1 server.


  1. Database Auto activation has been blocked on all copies on both EX16-01 & EX16-dr1 to safe guard from auto mount operations.
  2. DAG is configured in DAC mode (DagOnly), this is a must to ensure smooth DR operations (Data Center Switchover).
  3. Alternate Witness Server is Configured

Datacenter Switchover Procedure

Step1: Bring down Servers as planned (Or assume both the server are crashed due to some unforeseen issues at the Primary Datacenter, and we expect these servers to come up after restoring the services at Primary data center).

Shutdown EX16-02

Shutdown EX16-03

Check the cluster node status,


Get clusternode 1

Step2: Terminate the partially or failed Servers (in our case the server which are OFF)

[PS]>Stop-DatabaseAvailabilityGroup -Identity DAG02 -MailboxServer EX16-02 –ConfigurationOnly

[PS]>Stop-DatabaseAvailabilityGroup -Identity DAG02 -MailboxServer EX16-03 –ConfigurationOnly

Stop DAG Member

You may verify the DAG statistics by executing the following command.

[PS]>Get-DatabaseAvailabilityGroup dag02 | fl Name,st*,prima*,oper*,*wit*

DAG Status with stopstart servers

Step3: Stop the cluster service on all the nodes which are currently running and will be part of the cluster during the DR operations. It is important to terminate/switch off all failed partially failed servers in the DAG before we proceed to next step.

[PS]>Stop-Service clussvc

Note: Run the above command on all the running members, in our case EX16-01 & EX16-dr1.

Step4: Restore the DAG using Restore-DatabaseAvailabilityGroup command

[PS]>Restore-DatabaseAvailabilityGroup -Identity DAG02

Restore DAG

Note: if you have not configured the DAG with alternate witness server prior to this operations, you may provide the alternate witness server values along with the Restore DAG command.

The restore DAG operation may take extended period of time depends on the server resources and network latencies. Please do patient until it returns the results.

Step5: Remove the restriction on DB activation

With the above command, we have finished activating the DR mailbox servers. Now we can remove the activation restriction on the databases, so that the database will start mounting automatically.

[PS]>Get-MailboxDatabaseCopyStatus | Resume-MailboxDatabaseCopy

Satus check

Validate the status, you should find mailbox databases gets mounted automatically in a while.

You may also verify the cluster node status, by now only the nodes which are active will be listed.

ClusterNode AfterRemoval

Failback Procedure (Restoring Services to Primary Datacenter)

Let’s assume both the failed servers are now back online. Please verify that the cluster services are in disabled & stopped status on both these servers. BTW, restoring services is more easy and quick than failover/switchover procedure.

Step1: Put the Mailbox servers in the restored primary datacenter into a started state.

[PS]>Start-DatabaseAvailabilitygroup -Identity DAG02 -mailboxServer EX16-02

[PS]>Start-DatabaseAvailabilitygroup -Identity DAG02 -mailboxServer EX16-03

Start DAGMember

The warnings can be ignored safely.

Step2: Run Set-DatabaseAvailabilityGroup to commit the members back to cluster.

[PS] >Set-DatabaseAvailabilityGroup -Identity DAG02

During the course of this operation, the default settings of clusters will be brought back such as witness server, directory and other site settings if any. After the Mailbox servers in the primary datacenter have been incorporated into the DAG, it will take some time to synchronize the database copies.

With that we finished fail back procedure, as the database will be mounted automatically to the primary datacenters as we have not changed its activation preferences.

Final Status

You may also force to mount database by activating it through EMC or EAC.

Please share you experience in the form of comments, if any.


We often think how to Move Exchange Server 2016 to Different Active Directory Site. This kind of situation arises when you plan to extend the Messaging Infrastructure DR for Site resilience. Replicating small databases are possible by installing Exchange Server in DR site, however it may not be viable option replicate databases over narrow bandwidth if we plan to host bigger databases. From Exchange Server 2010, we can easily shift/move exchange server one active directory site to different AD Site by following simple steps outlined below.

1.  Ensure that you have created and replicated required AD site and Subnets for DR/Secondary datacenter.

AD Site Details

2.  Ensure that the Exchange Server Infrastructure is healthy, and all the databases are replicated properly.

DB Copy Status

3.  It is also recommended to check the AD and Exchange replication help using,

Test-ReplicationHealth from DR Exchange Server & nltest from DR Domain Controller

4.  Verify the current AD site status of Exchange Server

Before Moving Site Info

Before Moving Exchange Server Site Info

5.  Now we are good to initiate the server site migration. Before we shut down and physically move the server to different site, it is recommended to set the Exchange Server to Maintenance Mode.

.\StartDagServerMaintenance.ps1 -serverName EX16-DR1 -MoveComment SiteChange

And check the cluster status

Get-ClusterNode | ft name, dynamicweight, nodeweight, state -AutoSize

Move it to Maitenance


6.  Shutdown and Shift the server to new site (DR/Secondary data center) and Bring up the server with new IP range configuration (subnet should be aligned to DR site).

7.  Restart the Server once again to register required DNS entries and other connectivity.

8.  Follow the below commands and ensure that the site movement of DAG member is success

Get-ClusterNode | ft name, dynamicweight, nodeweight, state –AutoSize

And if the status is Pause, then everything is fine. If the status is Down, that means some connectivity issues, please continue to troubleshoot.

Get-ExchangeServer | select Name,Site

Ensure that the site has changed, if you find the value that you expect then proceed to remove the server from maintenance mode.

.\StopDagServerMaintenance.ps1 -serverName EX16-DR1

The server status will change to Up from Paused post this step, and it will begin to replicate the delta and eventually the database copies will become healthy.

Final Stages


That’s it,  you have completed the AD site change for Exchange DAG Member/Node.

Share you experience in the form of comments, we will deal whichever possible.


You may experience similar problems in version from Exchange 2010, here I have showcased an issue I faced in Exchange Server 2016 infrastructure.

You will see one or more of the following events/status on the server,

Event IDs 4026, 1009 etc.
Log Name:      Application
Source:        MSExchangeRepl
Event ID:      4026
Level:         Error
[Seed Manager] The seed request for database 'LAB-DB01' encountered an error during seeding. Error: An Exception was received during a FAST operation.


Log Name:      Application
Source:        MSExchangeFastSearch
Event ID:      1009
Task Category: (1)
Level:         Warning
The following information was included with the event:
Microsoft.Exchange.Search.Core.Abstraction.OperationFailedException: The component operation has failed. ---> Microsoft.Exchange.Search.Engine.FeedingSkippedException: "Feeding was skipped for '45fc6bd2-7221-4c3d-8314-4e6e75473703 (LAB-DB03)' due to the state 'Unknown', error code: 'Unknown'."


This issue can cause due to many factors, and most cases it can be mitigated by Solutions mentioned in the next section.

The reasons for this issues could be one or more of the following, but not limited to

  1. Issues with “Microsoft Exchange Search” (MSExchangeFastSearch) Service
  2. Issues with “Microsoft Exchange Search Host Controller” (HostControllerService) service.
  3. Corrupt Content Index
  4. Hard disk errors (read/write)

How to mitigate this issue, follow as suggested below!

Solution 1

Generally, this issue can be mitigated in one of the two list options below,

Option 1:

Consider you do not have any database copies with healthy Index State or the only server that host the database.

Stop the following services,

Microsoft Exchange Search Host Controller
Microsoft Exchange Search

Delete the folder similar to the following from database path/location.

Delete Folder

Start the Services in order,

Microsoft Exchange Search
Microsoft Exchange Search Host Controller

The Exchange Server will initiate the process to rebuild the whole index. Depends on the data/size the process may take extended period of time. Wait for the process to finish, and in 90% of the case it will fix the issue.

Option 2:

If you have one “healthy” Content Index state database copy, reseed the database copy that has the unhealthy copy of content Index. In some cases when you add database copy in the DAG, the content index can go into unhealthy status (such as failed, unknown, failedandsuspended etc). To recover the content Index back to healthy, you can reseed the content index by running the “Update-MailboxDatabaseCopy” command with switch “-CatalogOnly”.

Update-MailboxDatabaseCopy LAB-DB03\EX16-01 –CatalogOnly

If you already tried this command, you may get the warning “Seeding cannot be requested for the same database copy until the failed request has been cleaned up by the server …”. Please say “y” to proceed with the reseed operations.

Verify the ContentIndexState after sometime, you will see a “healthy” state.

Solution 2

If the above steps did not go through fine, and if you receive errors similar to below even if all these services are healthy then it will be not an easy task to bring back your ContentIndexstate to healthy.

WARNING: Seeding of content index catalog for database 'LAB-DB03' failed. Please verify that the Microsoft Search (Exchange) and the Host Controller service for Exchange services are running and try the operation again. Error: An error occurred while processing a request on server 'EX16-03'. Error: An Exception was received during a FAST operation..

In some cases, there are disk errors but in my case the server was recovered from a unexpected failure which lead to run recovery steps on the database. Post the recovery the ContentIndexState was in healthy status in some database copies, but did not work quite fine in others.

Please note that the Content Index State only impact the end user experience, you are still allowed to mount the database on server where the Content Index State is not healthy. Hence the recommended approach is to create additional database and move the mailboxes gradually to get rid of the problematic database.

In my case, I also had the following event (Event ID 40025) logged on the server where this database was active.

Source:        MSExchangeIS
Event ID:      40025
Task Category: High Availability
Level:         Error
       Database LAB-DB03 (45fc6bd2-7221-4c3d-8314-4e6e75473703) has been offline-repaired (by eseutil.exe) one or more times in the past. However, although this ensures database-level logical consistency and may permit the database to be successfully mounted, Exchange-level logical consistency can no longer be guaranteed. Therefore, all mailboxes should be evacuated from the database and the database should be retired as soon as possible in order to eliminate the potential for unexpected behaviour caused by Exchange-level logical inconsistency.      
This event will continue to be emitted once per hour while the database is mounted as an urgent reminder to evacuate and retire the database as soon as possible.      
Database last repaired: 3/15/2017 7:04:00 AM      
Repair count since the database was last offline-defragmented: 2      
Repair count before the database was last offline-defragmented: 0      
Recovery database?: False    
Please note that the above events and actions are based on Exchange Server 2016 infrastructure, however the operations are almost stays the same in other versions from 2010 onward.

Please share you comments or issues.



You may receive the following error when you tried to re-add a recovered Exchange 2016 Mailbox server back to Database Availability Group (DAG).

A server-side database availability group administrative operation failed. Error The operation failed. CreateCluster
errors may result from incorrectly configured static addresses. Error: An error occurred while attempting a cluster
operation. Error: Node EX16-01 is already joined to a cluster..

You may also see that the following error when trying to run the command "Set-DatabaseAvailabilityGroup". Please note I ran the command from the cluster node which I was trying to add to DAG.
The following servers in the Windows Failover Cluster are not in Active Directory: ex16-01. This is usually the result
of an incomplete membership change (add or remove) of the database availabilty group.

The above error usually the result of disabled cluster service, or AD replication errors.


It is evident that, some stale entries or communication error stops from adding recovered exchange server to the DAG cluster. Before you start any process to forcefully remove or add, try to do a force replication of Active Directory and repeat the usual procedures. If the results are same, follow the below process.

Run the following command from a healthy DAG Member.

1. Forcefully Remove cluster node which you failed to join the DAG cluster. In my case, I was trying to re-add the node ex16-01 back to the DAG02 Database Availability Group.

Get-ClusterNode ex16-01 | Remove-ClusterNode -Force

Wait for 10 - 15 minutes, so that the replication happens.

2. Run the command Add-DatabaseAvailabilityGroupServer with the node we want to add to cluster.

Add-DatabaseAvailabilityGroupServer -Identity DAG02 -MailboxServer EX16-01

3. Verify the Database Availability Group status,

[PS] C:\Windows\system32>Get-DatabaseAvailabilityGroup DAG02 | fl Name,Started*

Name : DAG02
StartedMailboxServers : {,,}

Following screen shot shows the chronology for your better understanding.


Post this, you may proceed with adding database copies or additional cluster operations.


This video help you understand the process of introducing or installing new version of Exchange, Exchange Server 2016 to existing environment. The LAB I have is with Exchange 2010 and not with Exchange 2013. But the process are the same to introduce the new exchange server. 

Ensure you went through the pre-requisites such as the minimum patch level, AD requirements etc. This video walks you through only the installation procedure and the time is not actual. 

The actual process may take anytime between 40 min to 90 minutes, do not disturb the process when feels no progress. You may just drag the Command windows to refresh the progress if any. 

I preferred to choose command line installation, much faster an easier.




Updates for all versions of Exchange Servers are now available on the Microsoft Download Center. First ever update for Exchange Server 2016, Cumulative Update 12 Exchange Server 2013 and Exchange Server 2007 and Exchange Server 2010 Update Rollups are available for the customers to download and patch.

More Details and Download Links,

Cumulative Update 1 for Exchange Server 2016 - Download CU1 ver 2016 

Exchange Server 2013 Cumulative Update 12 - Download CU12 ver 2013

Exchange Server 2010 Service Pack 3 Update Rollup 13 - Download RU13 ver 2010

Update Rollup 19 for Exchange Server 2007 Service Pack 3 (KB3141352) - Download RU16 Ver 2007

As always remember to test these updates to validate the compatibility with existing environment and the integrations if any.



A quick note on Exchange Team Blog (EHLO Blog) has mentioned that Exchange on-premises servers will run into some known issues if .NET Framework 4.6.1 is installed. Considering the impact, MS Exchange team has advised to delay the installation of .NET Framework 4.6.1 which is currently available through Windows Update.

It is worth thinking why MS has allowed it on Windows Update, without the confirmation from Exchange On-Prem team testing. We will yet to hear more updates on this, however it is highly recommended not to install the 4.6.1 update now.

Some of the reference articles for you to go through.

Exchange says no to .NET Framework 4.6.1

On .NET Framework 4.6.1 and Exchange compatibility


By now we are familiar with the concept of DAG. Database availability group is nothing but a set of up to 16 Exchange Server 2016 mailbox servers that provide high availability or automatic database recovery database-level recovery from a database level. It is an improved clustering operation from Exchange Server 2010 onwards. I recommend you to read more about DAG if you are not familiar with, as this article gives only an insight to DAG creation and database copy configuration.

Create Database Availability Group

1. Open Exchange admin center (EAC), and navigate to Servers

2. Click on Database Availability Group on the right pane of the console

3. Click on + sign to add DAG

4. Enter the required information such as DAG Name, Witness Server, Witness directory IP address etc. and click on Save button

Note: If you plan to use a domain controller as witness server, please add it to the Exchange Trusted Subsystem security group. In addition, add the Exchange Trusted Subsystem into the Administrators group

EAC - 1

This will create a Database Availability Group for you Exchange Server 2016 server.

DAG - EAC - 3 1

Add Members to DAG

1. Select the DAG name and click on Manage

2. Save once you add all required servers.

3. Now you can add database for High Availability.

DAG - EAC - 4

Note: The process will take some time, as the failover cluster feature will be installed during the member addition process. Please wait patiently until the operation is finished.

Add Database for High Availability

1. Create Database on one of the DAG Members (follow the usual steps)

2. Select the Database for which you need High Availability, and click on Add database copy from more option.

[Note: You might require to re-login to EMC in case if you did not find the Add database copy option]

3. Follow the wizard and select the server to which you need to replicate the database to.

4. Save the changes, all the required folder and files will be created automatically similar to ver 2010 & 2013.

DAG - EAC - 6


DAG - EAC - 7

After the successful addition of database copy, you would be able to see that the database copy on server X1 status is Active Mounted and copy on X2 is Passive Healthy.

Creating the DAG and Adding members to DAG operations are much faster when you use Shell commands, however the through GUI it becomes easy to understand.

I will cover more operation on DBs and DAGs in future posts. Share your suggestions to improve the quality of information.




Recently when I was installing and configuring Exchange Server 2016 on a LAB infrastructure to test some configuration, I encountered the following error,

Could not load file or assembly 'Microsoft.Exchange.Net, Version=, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The paging file is too small for this operation to complete. (Exception from HRESULT: 0x800705AF)

EAC .Net Error

Initially I thought, it was due to the resources of the server, where as it turned out to be in complete installation of pre-requisites for Exchange Server 2016. I did not bother to follow any document, instead I did it my own thinking that all steps are complete.


I was able to fix the issue by following the instruction below,

Step 1: Add the server feature Microsoft Media Foundation, by running the below command.

Install-WindowsFeature server-media-foundation

Step 2: Install the .NET Framework 4.5.2 if you missed during the pre-requisite preparation.

.NET Framework 4.5.2:Download

If you have already installed .NET Framework 4.5.2, try to repair and restart the server. It would solve the issue and you will be able to launch EMS and EAC easily.


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