No object code-set conversion (definition) file exists for the two given code sets. The environment variables DB_LOCALE or CLIENT_LOCALE might have been set to the wrong value, which caused an error condition to be generated. The files might also be missing, or the information that they contain might be garbled. Check the value of the environment variable CLIENT_LOCALE or DB_LOCALE. The object conversion files usually have the .cvo extension.
When accessing via drda protocol, this error may also mean that the client application is trying to bind a value which is in a different encoding than database locale. Set environment variable GL_USEGLU=1 prior to bringing up the server to initialize the appropriate converters required to handle the codeset conversions. (for example, when using setCharacterStream() interface to bind the LOB data through JCC, the input data may come with double byte encoding and may mismatch with DB_LOCALE)