For security reasons DTD is prohibited in this XML document.

Error

Failed: Message is: For security reasons DTD is prohibited in this XML document. To enable DTD processing set the DtdProcessing property on XmlReaderSettings to Parse and pass the settings into XmlReader.Create method.

Reason

This error message can sometimes occur when attempting to communicate with XML Web Services, such as those provided by Microsoft for Exchange / Office 365.

The problem itself can be caused by either:

• The configuration of the server that CloudM Migrate is connecting to. CloudM Migrate is expecting to communicate with an XML Web Service and receive a response containing well-formed XML. When it doesn't receive XML, but instead receives information in a different format, such as HTML, it usually fails with that error. HTML may be returned for a number of reasons such as a redirect to a login page or a custom HTTP 404 (page not found) error page.
• The migration server itself has some network/firewall issue/restrictions preventing it from accessing the source. Verify that DNS is correctly resolving the supplied address.

Example

An Office 365 admin has 2FA set to the MS App on a mobile device with an app specific password. This would typically return a custom HTTP 404 (page not found) error page.