Errors ORA-39083 and ORA-28365 during import

During an import you get:

ORA-39083: Object type TABLE:"SCOTT"."EMP" failed to create with error:
ORA-28365: wallet is not open

Action:
Open the wallet:

SQL> administer key management set keystore open identified by "mysecretpassword";

keystore altered.

Check status of the wallet:

select status from  v$encryption_Wallet;

STATUS
------
OPEN

You can now perform your import as you normally would.

After import you can Close the wallet:

administer key management set keystore close identified by "mysecretpassword";