IMP-00401: dump file may be an Data Pump export dump file
When I use original import utility to import data from a dump file, I got IMP-00401.
[oracle@primary01 oracle]$ imp \"/ as sysdba \" fromuser=erpapp rows=n indexes=y constraints=y grants=y ignore=n file=/oradata/dumps/exp_erpapp.dmp log=/oradata/dumps/exp_erpapp.log
...
IMP-00401: dump file "/oradata/dumps/exp_erpapp.dmp" may be an Data Pump export dump file
IMP-00000: Import terminated unsuccessfully
IMP-00401 means that you mistakenly use the original imp utility to import a dump file which is generated by data pump expdp. It's not allowable.
Solution
The solution is obvious, just use data pump impdp utility to import the dump file. For example:
[oracle@primary01 oracle]$ impdp \"/ as sysdba \" schemas=erpapp content=metadata_only directory=DATA_PUMP_DIR dumpfile=exp_erpapp.dmp logfile=exp_erpapp.log
That is to say, the dump files generated by original export and data pump are not interchangeable, you have to use the correct way to do it.