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Q: When I try to type my username and password into Kerberos Manager I get the error message "Kerberos returned an error Unknown code ____y91."


This error can occur on a Mac when one or more TCP/IP settings are not quite right. The more common cause is in the Search Domain entries being wrong or blank. It is also caused by using a TCP/IP address that has not been assigned a hostname by IS&T.

Search Domain setting is wrong or empty.

To correct this:

  1. Go to Control Panel > TCP/IP
  2. In the Search domains box, enter

Not an Assigned Network Address.

The best idea is to check with your department's person who assigns network addresses to be sure that your address is valid. That person will need to generate a valid address for you if needed, so you might as well get them involved from the beginning.

How can you tell if your address is valid? Consult this link to reach a list of all the currently assigned network addresses at MIT. Once you have the whole list loaded in your browser, use your browser's "Find" command to search for your address. If it's not in the list, then it's an unassigned network address and your departmental network person will need to provide you with a different one, or take steps to get your existing address officially assigned.

This article's original title was: When I try to type my username and password into Kerberos Manager I get the error message "Kerberos returned an error: Unknown code ____y91."

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Documentation and information provided by IS&T staff members

Last Modified:

August 08, 2014

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