ORA-24815: Invalid character set form
Cause: An invalid character set form was passed into an OCI LOB function. For example, the only valid cs form for OCILobCreateTemporary() is OCI_DEFAULT(0), SQLCS_IMPLICIT(1) or SQLCS_NCHAR(2).
Action: Specify a valid character set form.
ORA-24815: Invalid character set form is an error that is raised when an attempt is made to create a database character set with a non-existent form. The cause for this error is generally due to the session character set not being appropriate for the database character set.
Official Oracle Explanation:
This error is indicated when an attempt is made to create a database character set with a non-existent form.
Common Causes:
The most common cause of this error is that the session character set is not appropriate for the database character set.
Normal Processing:
To address this issue, it is first necessary to determine which character set/form combination is supported by the database and then configure the session accordingly. This can be done by querying the character set data dictionary view dba_char_sets and then modify the NLS_LANG environment variable on the client side. After the changes have been made, the session should be able to connect properly.