Troubleshooting server connection

No matter if you configure EWS connection to source/target Exchange Server or to source Office 365 tenant, the first action (test) performed by the program is always checking the connection to your server (Exchange Server or Office 365). During this operation, the software tries to access the mailbox of an admin account provided in the previous step of the wizard. If the result is negative (Fig. 1.), click the Details link on the right to see more information.

Exchange Migration EWS wizard failure 1
Fig. 1. Failure to connect to source Exchange Server.


To minimize the risk of connection errors, we advise to enable trust relationship between the source and target server.

Learn more about creating a forest trust on Windows Server 2008 and newer.

Study the examples below that show the most common server connectivity issues:

The request failed. The remote server returned an error: (401) Unauthorized.

The error message is produced when either the wrong target server administrator account has been chosen or the email address is different than the UPN (User Principal Name). You must make sure that provided credentials are the right ones and that they match the UPN. If you are still using the pre-Windows down level logons (DOMAIN\user) you must create a UPN for the purpose of the migration.

This error may also appear when configuring a connection to Office 365 by using an account that has multi-factor authentication (MFA) enabled. Enter the app password instead of your regular Office 365 password when providing the admin account credentials. You can also disable MFA for that account or use another account that is not MFA-enabled. Read more about managing MFA for Office 365 users.

The request failed. Unable to connect to the remote server.

This error occurs if the domain name in the administrator's email address is misspelled or the password is wrong. To fix the problem, go to the previous step of the connection wizard and make sure to enter correct credentials. A similar message is also shown if the EWS URL is wrong. In that case, go to the first step of the wizard and enter a correct EWS URL.

Failed to find in Active Directory an email address for [email address].

Exchange Server doesn't support the requested version.

These errors may appear when you choose a source/target Exchange Server version that is not supported by the program. When using EWS connection, CodeTwo Exchange Migration can be used to migrate mailboxes between the following versions of Exchange Servers: 2016, 2013, 2010 SP1, and SBS 2011.

The request failed. The remote server returned an error: (403) Forbidden.

The error message is produced when there is a problem connecting to the source/target server. Make sure you provided the right name or IP address of the server and the right EWS server address. To check this, you can copy-paste the EWS server address (EWS URL) from the program's settings into your web browser when you are logged in to the source server. If you don't get a credentials request pop-up window, this might mean that you provided wrong EWS server URL or IP.

Error: (407) Proxy Authentication Required.

Read more about this error in this Knowledge Base article.

Was this information useful?