Hi @Zullah,
Welcome to Box Community, and we will assist in resolving this error!
To ensure we help prevent bad actors from leveraging a compromised account and causing further damage by adding themselves as a new, fully permissioned admin account.
In that regard, all Box Administrators are required to only use verified domains. For more details, please check out this link.
If the affected user’s domain is unverified, here are the things you need to do.
Adding a managed domain consists of three separate tasks:
- Add the domain and get a unique code (also known as a hash).
- Create a new DNS record for the domain with the unique code.
- Validate the domain.
You can follow the complete instructions to this article.
Once you have successfully verified your managed user’s email domain, please go ahead and modify the user’s role.
Hope it helps!