Oracle Database Free

I'm getting various odd errors when I call:

select json_serialize( dbms_json_schema.describe( 'domain_name' ) pretty ) j;

Unfortunately, I can't reproduce them with a new Domain. (The ones that throw an odd error constantly throw the same odd error)

But, it does suggest there are problems within the function itself. (If I rebuild the Domain, I get the expected result/error)

ORA-00911: �nvalid character after )
ORA-06512: at "SYS.DBMS_JSON_SCHEMA", line 237
ORA-06512: at "SYS.DBMS_JSON_SCHEMA", line 280

ORA-02252: check constraint condition not properly ended
ORA-06512: at "SYS.DBMS_JSON_SCHEMA", line 237
ORA-06512: at "SYS.DBMS_JSON_SCHEMA", line 280

-- I lost the actual error message and line numbers
ORA-00991 --- concatenator is || not |

other (reproducible problems)

• 'domain_name' needs to be UPPER
• dbms_metadat.get_ddl does not work for object type DOMAIN (how do I get the DDL for a Domain?)
• multi-column domains are not supported (missing feature)

I wish I could be more helpful.