ORA-39002: invalid operation EXPDP operation Oracle

Error
During execution of EXPDP the following error occur:

ORA-39002: invalid operation
ORA-39070: Unable to open the log file.

Solution
Step 1: Check the directory parameter in EXPDP command.

EXPDP directory=dbbackup dumpfile=prod.dmp logfile=prod.log

Step 2: Check the directory exists in database

sqlplus / as sysdba
select * from dba_directories;

Step 3: Check the directory path exists at operating system level as mention in dba_directories.

This three steps solve the problem.