I am trying to chnage user role on app store connect from role Developer and Marketing to App Manager. And after selecting App Manager role option under Roles menu getting following error.
Is there something related to roles and access or it's just a server error?
Try to unclick the "Create Apps" role access under "Additional Resources" and then assign the "App Manager" role.
It seems that if the Create Apps role already exists the new role cannot be assigned.