Troubleshooting the change subtype command-prompt utility

The command-prompt tool that changes the subtype of a contact instance is described at Changing subtype with a command-prompt utility. When you run this command, the following errors can be reported in the console.

Error message	Cause of the error
`Failed to change contact to subtype: Bad username or password`	Any of the following entries could have caused this problem: You entered an invalid user name. You entered the wrong password. You entered the password without a user specified and you are not using the password of the Super User. Unless you are user Super User, the default user for this command, you must use the -user parameter and specify a user that has the permissions `changecontactsubtype` and `soapadmin`. For example, the role Contact Subtype Changer has these two permissions.
`Failed to change contact to subtype: Incorrect runlevel for subtype change. Required: MAINTENANCE, Actual: MULTIUSER`	You have not set the application runlevel to `maintenance` prior to running the command. Use the following command: `system_tools -password adminuser-password -maintenance`
`Failed to change contact to subtype: Contact with PublicID public-id-value not found`	You entered an incorrect value for the PublicID of the contact.
`Failed to change contact to subtype: entity-name is not a valid entity type`	The entity name you used is not valid. For example, you used `ABDoctor` in ClaimCenter, or `Doctor` in ContactManager.
`Failed to change contact to subtype: entity-name is not a valid subtype of Contact`	The entity name you used for the new subtype is not a subtype of `ABContact` or `Contact`. For example, you tried to change the contact subtype from `ABPerson` to `ABContact`.
`Failed to change contact to subtype: Cannot change Person to Company/Place or Company to Person/Place for contacts with Client tags`	The contact has a Client tag, which makes the contact usable by PolicyCenter and BillingCenter. Those applications do not support changing between a `Person` contact subtype and a `Company` or `Place` subtype. See Subtype changes for client contacts.
You see the list of command-prompt options for `maintenance_tools`, but no error message	Either you misspelled one of the command-prompt options or you did not enter one. Changing a contact subtype requires that you enter both options, -changesubtypetargettype and -changesubtypepublicid. See Changing the subtype of a Contact instance.