Please provide steps to reproduce the error.

• Go to Special:RequestCustomDomain
• type in br3xawikiwiki for the target database name

*admire the error

What happened that shouldn't have?
says "The provided target is not a valid database name."

What should have happened?
it should have accepted my request.

Provide a link to Special:Version for the site you're experiencing this on.
https://meta.wikioasis.org/wiki/Special:Version