Welcome to Q&A Forum; this is a great place to get support, answers, and tips.
Thank you for posting your question; I'll be more than glad to help you out.
As you didn't supply much information on what you are trying, my answer might lead in the wrong direction...
1.) There is a patch from Oracle for 19C on this error
2.) Maybe you are running into an issue that can be fixed with a 4-part query or you might find some help here:
I hope my answer is helpful to you,
If the reply was helpful, please upvote and/or accept it as an answer, as this helps others in the community with similar questions. Thanks!