Cause
Single byte lexer selected in multibyte language setting
Single byte lexer selected in multibyte language setting
check RDBMS language setting or text columns lexer setting
Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/drgus.htm
https://community.oracle.com/message/132969
https://community.oracle.com/message/2488635
https://community.oracle.com/message/455748
https://community.oracle.com/message/78635
https://community.oracle.com/message/90398
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