Oracle ora-12801

Hi,

I saw today an error in the alert-log of one of our Oracle 12.2 database. It was a trace file with one simple query:

SELECT DISTINCT constraint_name,

              table_name,

              owner,

             constraint_type

FROM all_constraints

WHERE   ((owner = N'XXXXX') AND (table_name IN (N'YYYY')))

         AND constraint_type IN ('P', 'U');

This query gives the following errors:

ORA-12801: error signaled in parallel query server P000

ORA-00600: internal error code, arguments: [kpp_concatq_cs:2], [7], [6], [0],

The combination ora-00600 with kpp_concatq_cs can't be found on Metalink. And if I remove the n-string (N'XXXXX' -> 'XXXXX') the query executes without a problem. Is this a know issue?