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Failed to Communicate with the Mailbox Database

Ravi Singh  | Updated on November 26, 2020 | EDB to PST Converter   | No Comments   | 4 min read

Summary: In this guide, we discussed a common Exchange error, “Can’t remove move request – Failed to communicate with the mailbox database” that appears when Exchange admins attempt to move a mailbox from one Exchange server to another. This may occur due to size limit, network issue, low storage space on the target server, or lack of required permissions or access to the server. With the help of methods discussed in this guide, you can easily resolve the error and move mailboxes to another server.

While migrating to another Exchange server, Exchange admins also need to move mailboxes from the old server to the new Exchange server. This can be done by using the New-MailboxExportRequest cmdlet. Although the process is quite easy, there could be instances where mailbox migration may fail due to lack of permissions, connectivity issues, etc. In such cases, an error message, “Failed to communicate with the mailbox database” may appear.

The error may also appear when you attempt to remove or clear pending or stuck mailbox move requests via Exchange Management Console (EMC).

Failed to Communicate with the Mailbox Database

In this guide, we’ll discuss various methods to troubleshoot and resolve this error by using various Exchange utilities and options. Also, discuss about an Exchange EDB to PST converter software that can migrate mailboxes from the old Exchange server to the new one in a few clicks.

Reasons for Error “Failed to communicate with the mailbox database”

There could be various reasons that may lead to this error while creating or removing the mailbox export or move request in the Exchange server. These are:

  1. Lack of required permissions
  2. Network issues
  3. New server is not connected or running
  4. Low storage space on the target server
  5. Damaged Exchange database or mailboxes

Methods to Fix ‘Failed to Communicate with the Mailbox Database’ Error

Following are a few methods that you may follow to troubleshoot and fix this error. After fixing the error Failed to communicate with the mailbox database, you can re-attempt to move the mailboxes from old Exchange server to the new one. However, if these methods do not help, you can always rely on an EDB to PST converter software, such as Stellar Converter for EDB.

Unlike manual methods and Exchange utilities, such as EMC, EAC, or EMS, this EDB to PST converter doesn’t require any permissions except server admin credentials and access to the database file that contains mailboxes on the old server. This GUI-based software scans EDB files and displays all mailboxes and mail items, along with options to search, sort, or filter the results for quick migration. You can select the mailboxes and then export them directly to a live Exchange server (in the same forest).

It also exports mailboxes from decommissioned, failed, or inaccessible Exchange server database to live Exchange, Office 365, and Outlook importable PST format.

Method 1: Check Permissions

To run various cmdlets to move or export mailboxes from the Exchange server, you require additional permissions and roles, such as the Mailbox Import Export role. These roles and permissions are not even assigned to the administrator account. If the required permissions are not assigned, the user may face the ‘Failed to Communicate with the Mailbox Database’ error message. Thus, you must assign the required permissions to run the move or export mailbox cmdlets for migrating the mailboxes.  

You can use the Active Directory to assign these permissions. Here’s how,

  • Open Active Directory and navigate to View > Enable Advanced Features
  • Then find the user account that you are using for mailbox migration
  • Click on Properties and then go to Security > Advanced
  • Click on the “Allow inheritable permissions from the parent to this object and all child……..checkbox and then click OK twice to confirm and save the settings
  • Then restart the target Exchange server and attempt to move the mailboxes again

Method 2: Check the Network Connection and Target Server

Sometimes, network issues may create trouble while migrating mailboxes from one Exchange server to another. Check the network connection and also verify the server port. Also, ensure that the target server is up and running.  

Method 3:  Remove Request via ADSIEdit.msc

Sometimes, an attempt to remove a pending or stuck move or export mailbox request fails. In such cases, you can use the ADSIEdit.msc to remove any pending or stuck requests. This helps troubleshoot and fix the mailbox database communication error. To remove requests via ADSIEdit.msc, follow the given steps:

  • Press Windows+R, type ADSIEdit.msc, and press ‘Enter’ to open ADSIEDIT
  • Then navigate to Connect to > Default Naming Context > DC={your domain}, DC={your domain extension}
  • Locate the affected user account and then right-click on it
  • Choose “Properties” and then click on the “Filter” button. Make sure “Show only attributes that have values” is checked
  • Then scroll down the attributes and search for the following entries,
    • msExchMailboxMoveRemoteHostName
    • msExchMailboxMoveFlags
    • msExchMailboxMoveStatus
  • Click on the “Edit” and then click on the “Clear” button. Repeat until all three entries are cleared
  • Click the “OK” button

This removes any pending move requests. You can recheck the move requests section to confirm if the requests are removed.


The error ‘Failed to communicate with the mailbox database’ usually appears while migrating the mailbox from one Exchange server to another. It obstructs the migration process and causes delays that can be avoided by using an Exchange migration software, such as Stellar Converter for EDB. The software facilitates quick and easy migration of mailboxes from the old server to the new live Exchange server directly or PST format, without any additional permissions. The software can be used to migrate mailboxes from a working, failed, or decommissioned Exchange server to Office 365, live Exchange, or existing Outlook profile in a few clicks, thereby helps avoid downtimes.