One may encounter this error while importing from a dmp file from older versions of Oracle. Genereally this error is caused by some statement like alter session set current_schema=scott; And the simple reason is that the user scott doesn’t exist. Yesterday I came across this error. And the reason was that user was not created. As in case of import we generally create tablespaces first (by creating the DDL using option show=Y) but creation of users is done by import itself. In older versions of Oracle, the temp tablespaces were no different from other tablespaces. But in newer versions temp tablespaces are different. So in dmp files from thoese older versions create user statements are written like create user t1 identified by t1 default tablespace temp temporary tablespace temp. This thing worked fine in older versions but in newer versions we cannot specify the TEMP tablespace as the default tablespace for a user. So the statement create user t2 identified by t2 default tablespace temp temporary tablespace temp throws ORA-12910: cannot specify temporary tablespace as default tablespace. In such cases the users (for which default statement is specified as TEMP) have to be created manually by specifying the appropriate tablespace as default tablespace and then the import should be run with ignore=Y.

Sidhu