ruby on rails - Why do I now get the error ActionView::MissingTemplate: Missing template user_mailer -- when the template exists already? -

on application have been sending out email messages, until today. when run rake task or run method mannually console, following error:

usermailer#admin_test: processed outbound mail in 23.6ms actionview::missingtemplate: missing template user_mailer/admin_test         "mailer". searched in: * "user_mailer" 

this lead me check if there template, there in user_mailer/admin_test.html.erb , user_mailer/admin_test.text.erb .

my method in user_mailer.rb is:

def admin_test(user)   @user = user   mail(to: @user.email, subject: "text") end 

running usermailer.admin_test(@user).deliver_now! (or deliver!) renders error. came upon running rake task scheduler , error replicated straight console.

edit

here's rest of error message:

from /users/xxxx/.rvm/gems/ruby-2.2.1/gems/actionmailer-4.2.1/lib/action_mailer/base.rb:915:in `each_template' 

edit 2

okay - pushed current form heroku , working in production not in development.