When entering the Challenge Code for the "Offline Password Reset" workflow the following error may be returned and a response code is not given.
"Several computers matching the challenge code were found. Contact your administrator for assistance."
This error will also appear in the 'QPM_Service_Host....' verbose log.
There are duplicate computer accounts in the domain.
When a challenge code is created it is made up of a number of components such as domain & username. The computer ID is also one of the components in the challenge code.
When this code is entered into the PM Site it is parsed and each component is examined by Active Directory (AD)
If AD determines that there is more than one computer with the same ID in the domain the it will not be possible to reset the password and produce a response code.
This problem is external to Password Manager.
A systems administrator must check for duplicate computer accounts in AD.
Once found the duplicate must be deleted. Disabling the account will not fix the issue.