"Invalid character" when using "?" as parameter in "Explain Plan"

I cannot use "?" while doing Explain Plan. For example, if we do "Explain Plan" on the following

select * from DUAL WHERE DUMMY = ?;

it only returns ORA-00911: invalid character.

Does anyone know how to fix this?


The server output is:

HR> EXPLAIN PLAN SET STATEMENT_ID = 'oj0tgh/14pN9ZXg4J/hA6Q==' INTO "PLAN_TABLE" FOR select * from DUAL where dummy = ?
[2022-11-09 11:42:20] [22019][911] ORA-00911: invalid character
[2022-11-09 11:42:20] Position: 114