Expdp export encountered ORA-39064: unable to write Log File

Expdp export encountered ORA-39064: unable to write Log File

Expdp export encountered ORA-39064: unable to write Log File

.. Exported "USER_XXXX". "TAB_YYYY" 0 KB 0-line ORA-39064: unable to write Log File ORA-29285: file write error

After searching for mos, the following articles provide solutions:
Error ORA-39064 Might Be Encountered By DataPump Export (EXPDP) When NLS_LANG Is Different From Database Character Set (Doc ID 1321034.1)

The solution provided in this solution is: Please set the character set in environment variable NLS_LANG to database character set.

This mos article is reproduced in the following full text without translation:

Applies:

Oracle Database-Enterprise Edition-Version 10.1.0.2 and later
Information in this document applies to any platform.
*** Checked for relevance on 15-Apr-2013 ***

Symptoms

In a multi-byte character set environment, if the client variable NLS_LANG is set to a character set which is different from database the character set, then DataPump export may encounter errors like:

ORA-39064: unable to write to the log file
ORA-29285: file write error

The Utilities manual specifies:

"Note: Data Pump Export writes the log file using the database character set. if your client NLS_LANG environment setting sets up a different client character set from the database character set, then it is possible that table names may be different in the log file than they are when displayed on the client output screen."

Cause

This was investigated in Bug 6136923 (closed as 'not a Bug ') with reference to unpublihsed documentation bug 3174256.
DataPump internally uses the package UTL_FILE and this does not correctly return the characters during NLS conversion.

Solution

Please set the character set in environment variable NLS_LANG to database character set.

The following information was added to manual:

Oracle Database PL/SQL Packages and Types Reference
Using UTL_FILE:

"When data encoded in one character set is read and Globalization Support is told (such as by means of NLS_LANG) that it is encoded in another character set, the result is indeterminate. if NLS_LANG is set, it shoshould be the same as the database character set."