Symptoms
In Microsoft Outlook 2016 or Outlook 2013, you experience one or several of the following symptoms:
- You receive the following error message:
The Microsoft Exchange Administrator has made a change that requires you quit and restart Outlook.
- You receive the following error message when you start Outlook:
Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened. The file C:\Users\<username>\AppData\Local\Microsoft\Outlook\user@doamin.com.ost is not an Outlook data file (ost).
- Outlook displays one of the following message in the status bar:
Trying to connect…Disconnected
Cause
This issue occurs if there is a trailing space (that is, if a space is the last character) in the legacyExchangeDN attribute.
Resolution
To resolve this issue, remove the trailing space from the legacyExchangeDN attribute by using ADSIEdit.msc. To do this, follow these steps.
Important After you make this change in the legacyExchangeDN attribute, recipients who previously received an email message from this user will receive a non-delivery report (NDR) message if they try to reply to an email message that they received from this user before the change was made. This problem will not occur for replies to new email messages that the user sends after the change was made.
- Open the Run dialog box. To do this, use one of the following methods, as appropriate for your situation:
- Windows 10, Windows 8.1 or Windows 8: Press the Windows key + R.
- Windows 7 or Windows Vista: Click Start, and then click Run.
- Type ADSIEdit.msc, and then press Enter.
- Expand the Default naming context to CN=Users.
- Select the user account whose mailbox is prompting the error.
- Right-click this account, and then click Properties.
- Locate the legacyExchangeDN attribute, and then click Edit.
- Remove the trailing space at the end of the username.
- Click OK, click Apply, and then exit ADSIEdit.msc.
- Have the user exit and then restart Outlook.
Source: Microsoft