ORA-43926
Cannot use the specified collation with some of the dependent objects.
Cause
An attempt was made to change the collation of a character column to a collation that is not supported in a key of a bitmap join index, a domain index key to which the column belongs. Only the collations BINARY, USING_NLS_COMP, USING_NLS_SORT, USING_NLS_SORT_CS, USING_NLS_SORT_VAR1, and USING_NLS_SORT_VAR1_CS are supported in these keys.
Action
Use one of the supported collations for the key column.