Glyn Millington <glyn.millington@gmail.com> writes:

> Greetings!
>
> Emacs 24.4.1 (Arch Linux if that helps)
> Notmuch 0.19
>
> The problem is that I can neither compose a new email nor reply to an old
> email unless I have already used  message mode (via Gnus) first.
> I get an error message - Google on the error message below gets me nowhere!
>

Can you duplicate the error with a minimal .emacs? In particular save
the following to "run-notmuch.el" and start emacs with

% emacs -Q --load run-emacs.el

;; -8x-------------------------------------------------------------
;; adjust the following line to point to either the .el or .elc of
;; notmuch.el

(add-to-list 'load-path "/path/to/notmuch/dot/el")
(require 'notmuch)
(notmuch-mua-mail)

;; -8x-------------------------------------------------------------

If that doesn't error, then the most likely trigger is some setting or
add on package in your .emacs. Once we know what the trigger is, we can
try to figure out where bug lies.