Installing ghc-mod from melpa: Error during download request

I am following the instructions here to install ghc-mod in Emacs. I can add the melpa repos and list packages with M-x package-list-packages, then when I go to install the ghc package, this happens:

Debugger entered--Lisp error: (error "Error during download request: Not Found")
  signal(error ("Error during download request: Not Found"))
  error("Error during download request:%s" " Not Found")
  package-handle-response()
  package-download-tar(ghc "20141130.1848")
  package-download-transaction((ghc))
  package-install(ghc)
  mapc(package-install (ghc))
  package-menu-execute()
  call-interactively(package-menu-execute nil nil)

In .emacs I have

(require 'package)
;; Add the original Emacs Lisp Package Archive
(add-to-list 'package-archives
         '("elpa" . "http://tromey.com/elpa/"))
; old url for melpa
;(add-to-list 'package-archives
;             '("melpa" . "http://melpa.org/packages/") t)
(add-to-list 'package-archives 
     '("melpa-stable" . "http://melpa-stable.milkbox.net/packages/"))
;; Add the user-contributed repository
(add-to-list 'package-archives
         '("marmalade" . "http://marmalade-repo.org/packages/"))
(package-initialize)

I am using emacs 24.3.1 on ubuntu. How to proceed? Thanks.

[EDIT] I installed this package successfully by downloading it myself but I'd still like to know what's wrong here.

Solution

It looks like you may have started working with MELPA (not MELPA stable):

You have the MELPA package repository in your .emacs (though commented out), and
The traceback shows that you were trying to install version 20141130.1848, which is a MELPA-style timestamp.

But MELPA is disabled in your init file by the commenting. You also have MELPA stable listed, which uses a different versioning scheme based on Git tags instead of on build timestamps. The latest version of ghc in MELPA Stable is currently 5.2.1.2.

I think you may have made this change without running package-refresh-contents, which updates your local package list. (Note that this is often done automatically, e.g. by loading the package list with package-list-packages).

So when you tried to install ghc, based on the stale package list that Emacs had it looked for version 20141130.1848, but could only find version 5.2.1.2. Try again after running M-x package-refresh-contents.

Note that you also have Marmalade enabled, which also contains ghc (version 1.10.2).

Since there is some package overlap between MELPA and Marmalade, I don't recommend using both concurrently. You can manually pin packages to one repository, but this gets to be a pain. I switched to MELPA Stable exclusively a few months ago, and I've been very happy with it.