You can receive the error message 'Error ORA-01041: internal error. hostdef extension doesn't exist' when attempting to re-establish a connection to Oracle with ERwin. This can happen for example when repeating the Complete Compare process.
Locate the 'sqlnet.ora' file and set:
SQLNET.AUTHENTICATION_SERVICES = (NONE)
Posted: 21 May, 2012 by Weissenberger K.