After performing an upgrade or new install to Password Manager 5.8 the Admin Site is no longer accessible with correct credentials.
The following error will be present in the Event Viewer:
System.ArgumentNullException: Value cannot be null.
Parameter name: virtualPath
at System.Web.VirtualPath.Create(String virtualPath, VirtualPathOptions options)
This is caused by the following scenarios:
1. An absent item represented with a GUID in one or more of the following Local Groups:
2. The Password Manager service account is configured to use a local account (not Domain account).
3. The "Authentication Failed" message means that the account trying to login is not a member of the PMAdmin group on the machine.
This has been logged as defect ID TF00776930: Unable to access Admin Site after upgrade to Password Manager 5.8.
A hotfix is available to resolve this issue: