On Wed, Oct 4, 2017 at 3:13 PM Haider Rizvi <harizvi@gmail.com> wrote:
I'm getting the following error, when trying to do an org-capture.

Debugger entered--Lisp error: (error "Invalid file location: nil")
  signal(error ("Invalid file location: nil"))
  error("Invalid file location: %S" nil)
  org-capture-expand-file((concat org-directory "inbox-gtd.org"))
  org-capture-target-buffer((concat org-directory "inbox-gtd.org"))
  org-capture-set-target-location()
  org-capture(nil)

My org-capture-templates is set as follows for ages:
(setq org-capture-templates
      '(("t" "Todo" entry (file+headline  (concat org-directory "inbox-gtd.org") "Tasks")

Org 9.1 onwards, bare sexp's are now allowed in the template.

From ORG-NEWS:

*** ~org-capture-templates~ no longer accepts S-expressions as file names

Since functions are allowed there, a straightforward way to migrate
is to turn, e.g.,

: (file (sexp))

into

: (file (lambda () (sexp)))

Reading up org-capture-expand-file, it seems org-directory is
prepended automatically,

correct
 
but it used to work fine in the
past. Flipping back to the older code for org-capture-expand-file
works fine. So I'd say this is a bug!

As mentioned above, this is expected. 
--

Kaushal Modi