The user attempted to set statistics_level to BASIC with auto-tune SGA enabled which cannot be done because auto-tune SGA cannot work with statistics_level set to BASIC.
Disable auto-tune SGA and try setting the statistics_level to BASIC again.
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Try the following links for this error:
http://docs.oracle.com/cd/E16655_01/server.121/e26079/e0.htm
https://community.oracle.com/message/2572918
https://community.oracle.com/message/1319649
https://community.oracle.com/message/1592095
https://community.oracle.com/message/3567317
https://community.oracle.com/message/3658204
https://community.oracle.com/message/10702402