
A missing first or last name value for the user causes this issue. It is mandatory to enter the "First Name" field while creating an archive from the Veritas Alta Archiving Manage portal, however synchronizations of Cloudlink and/or Office 365 Sync allow archives to be created without both First & Last Name. This is because most mail platforms do not require both first and last name fields, and Veritas Alta Archiving does require both.
This generally happens with archives of shared mailboxes (mailboxes not tied to an Active Directory user). When such a user attempts to login, the above error is thrown.
Login to Veritas Alta Archiving Manage portal and update the "First Name" field for the affected archive.