How to Solve the Error “Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group”?

Media Team | Modified: 2021-03-26T15:08:44+00:00 | Error, Exchange Server|

Summary: “Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group” error occurs when users try to open the Add-Ins section in the Microsoft EAC (Exchange Admin Center) under organization. This can happen when the Exchange databases is dismounted because of corruption or either the Microsoft Exchange Server services aren’t running or stopped because of the problem with the server. This write-up will help users and guide to fix the error and recover the Exchange EDB file from corruption via SysTools Exchange Server EDB Recovery Tool.


Microsoft Exchange Server work in every IT organization and other industry verticals around the world. It provides many functionalities, services, security, etc… to the users and one such feature is add-ins for the MS Outlook users. This feature increases the ability of Outlook clients or its users with the addition of tools as well as information that is suitable or compatible with Microsoft Outlook.

Everyone knows that the add-ins feature in the Exchange Admin center is the third-party application that add value to the application. Users can install these via URL, offline store, or the file. It is not recommended to install any wrong third-party add-ins which directly affect the communication or functionality of MS Outlook. The duty of the Exchange administrator is to provide a smooth system where you have those tools that users need for controlling & collaboration of the installation. You can do this via EAC (Exchange Admin Center). It provides the roles as well as help them to control users ability to install the add-ins feature.

For this users have to Login the Exchange Admin Center >> Click on the organization >> Then, select the Add-ins

Here, you can remove, add & control the add-ins feature to install but sometimes while accessing this tab the error generates which says

“Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group
(FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn=MB01/cn=Microsoft System Attendant”

cannot open mailbox /o=first organization/ou=exchange administrative group

Things Required to Fix the Error “Cannot open mailbox /o=First Organization/ou=Exchange Administrative Group”

The first & foremost thing is to check that all the Microsoft Exchange Server services are running & ensure that also the service which are set to automatic is started.

Then, check that all the Exchange Server databases are mounted & healthy. Users can do this by login to the EAC (Exchange Admin Center) >> Select the servers >> Databases

After that check all the Exchange database is mounted, if any of the databases is not mounted then you have to look into this matter further.

Therefore, in Exchange Server & the drive where Exchange log file and database are store have enough storage space. Size issue is one of the major reason because of which the Exchange database is not in a mounted state and the prime cause is the corruption occurs in log and EDB file.

After that, verify or check the Exchange Server license which is installed in opposition to Exchange databases that are configured. The standard version allows only 5 online databases and the rest will be dismounted. The solution to this problem is that users have to delete the spare database or else what you can do is buy the Exchange Server Enterprise License but it is not cheap, make sure before purchasing it and also ensure that it is required for your business.

If you have an additional or the older Exchange database, in that case users can use the Exchange PowerShell New-MailboxExportRequest to export all mailboxes to PST file from Exchange Server. Other than this if you have Exchange public folder then it will be little bit more complex to export it to Outlook Data File because for this you have to use the script to extract the Exchange data.

To avoid this complexity users can use the Exchange Server EDB Recovery Tool which supports both offline / dismounted public and private Exchange database as well as streaming media file and allow users to bulk export Exchange public folder to PST file along with private EDB file in a simplified manner.

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Also check the third-party application such as: antivirus, backup software, etc… that is install in the Exchange Server is compatible with it or not. If it isn’t compatible then it could affect the performance, operation and it could corrupt the Exchange data.

The other reason is corruption in Exchange database file which occurs because of software as well as hardware failure such as: power outage, broken motherboard, etc… When the EDB isn’t get mounted safely then it results in the corruption of the log and .edb file.

For starters, users have to use the ESEUTIL utility to check the state of dismounted / offline database. For this, use the command given below:

mh command


dirty shutdown

When the Exchange database is in a clean shutdown state, then you can easily mount the EDB but it is not mounting then it can be because of corruption or the missing log file and the state of the database is shown as Exchange dirty shutdown state.

Users can repair the database by performing the soft recovery and hard recovery in Exchange 2010, 2013, 2016.

To perform the soft repair you have to run eseutil /r command and bring the state of the Exchange database in a clean state. After executing this cmdlet, again check the state of the database via eseutil /mh. If the state is in dirty shutdown then you have to perform the hard repair by using the eseutil /p command which is given below:

Note: Use this cmdlet is there is no choice left because it may purge the Exchange data or corrupt it and users cannot recover the data backup after running this command & there is no surety that this will bring the database in a clean state. To avoid all this complexity you can use the advanced software described here which easily fix Exchange database corruption without using any cmdlet in a simplified manner.

After executing the command a dialogue box will appear that asks you to proceed. Click OK if you want to go ahead.


eseutil p message

Use Alternative Solution to Recover the Exchange Database From Corruption

Exchange Server EDB Recovery Tool easily recover, repair EDB file and mailboxes from corruption with no data loss. The software support offline/dismounted Exchange database file and it provides Quick and Advance scan option which easily recovers and repair Exchange mailbox along with .edb file from minimal and major corruption without using any command. As it provides the graphical interface which makes the users work easier and save their time as well as effort too.

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After recovery, you can extract mailbox from EDB file Exchange 2013/2016 and export it directly to the Live Exchange Server mailboxes, Office 365, and various file formats (HTML, EML, MBOX, MSG, PDF, PST). Technical and non-technical users can use this recovery manager for Exchange database utility and it auto-generates the export report in CSV file format which contains the success and fail count of exported Exchange data. It supports all versions of Microsoft Outlook, Exchange Server and Windows OS.

Bringing It All Together

Now users have detailed information about how this error occur and how to fix “cannot open mailbox /o=first organization/ou=exchange administrative group” by using the solution mentioned here. In case of minor & highly corrupted offline / dismounted Exchange database file it is suggested to use the automated wizard described in the above section which easily recovers and repair the corrupted Exchange database without any hindrance and allows users to import EDB into Exchange Server 2016, 2013, 2010 & below version in a simplified manner.

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