Here's the definition from the docs:
Either an attempt was made to issue an ALTER SESSION command with an invalid NLS parameter or value; or the environment variable(s) NLS_LANG, ORA_NLSxx, or ORACLE_HOME was incorrectly specified, therefore the NLS data files cannot be located.
Check the syntax of the ALTER SESSION command and the NLS parameter, correct the syntax and retry the statement, or specify the correct directory path/values in the environment variables.
This would occur when trying to import tables into the RPD (OBIEE). First thing that pops up is the Select Data Source screen:
Then this beauty would pop up:
Ultimately the solution that, sort of worked, was here.
We tried changing it to what I had in my registry: AMERICAN_AMERICA.WE8MSWIN1252
That didn't work.
Tried renaming it as the article suggested, that didn't work.
Finally, my colleague (without prompting from me), cleared the key (didn't delete, just blanked it)...and voila!