Hi there,

When I use crossref-add-bibtex-entry it download the BibTeX entry but cannot download the associated pdf.
I get the following error  (wrong-type-argument stringp ("/Users/doyley/Dropbox/Filing_Cabinet/B/refs/pdf/“))

I configured org-ref as follows

(setq org-ref-bibliography-notes '("/Users/doyley/Dropbox/Filing_Cabinet/B/refs/ref_notes.org") 
      org-ref-default-bibliography '("/Users/doyley/Dropbox/Filing_Cabinet/B/refs/ref.bib") 
      org-ref-pdf-directory '("/Users/doyley/Dropbox/Filing_Cabinet/B/refs/pdf/")
 org-ref-notes-citation-link '("cite")
      )

(setq bibtex-completion-bibliography  '("/Users/doyley/Dropbox/Filing_Cabinet/B/refs/ref.bib") 
      bibtex-completion-library-path '("~/Org-files/Notes/PDF"))

(setq bibtex-completion-notes-path "~/Org-files/Notes/ref_notes.org") 
(setq bibtex-completion-pdf-symbol "⌘")
(setq bibtex-completion-notes-symbol "✎")



Also enclosed is the backtrace
Thanks for your help in resolving this issue 
M

Debugger entered--Lisp error: (wrong-type-argument stringp ("/Users/doyley/Dropbox/Filing_Cabinet/B/refs/pdf/"))
  file-name-as-directory(("/Users/doyley/Dropbox/Filing_Cabinet/B/refs/pdf/"))
  doi-utils-get-bibtex-entry-pdf(nil)
  funcall-interactively(doi-utils-get-bibtex-entry-pdf nil)
  call-interactively(doi-utils-get-bibtex-entry-pdf record nil)
  command-execute(doi-utils-get-bibtex-entry-pdf record)
  helm-M-x-execute-command(doi-utils-get-bibtex-entry-pdf)
  helm-execute-selection-action-1()
  helm-execute-selection-action()
  helm-internal((((name . "Emacs Commands history") (candidates . #f(compiled-function () #<bytecode 0x1ffd35a88d85>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal stat..." ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert stat..." ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert nor...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keep...") (must-match . t) (group . helm-command) (match-dynamic . t)) ((name . "Emacs Commands") (candidates . #f(compiled-function () #<bytecode 0x1ffd3626ae55>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal stat..." ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert stat..." ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert nor...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keep...") (must-match . t) (group . helm-command) (match-dynamic . t))) nil "M-x " nil nil "*helm M-x*" nil nil helm-M-x-input-history)
  apply(helm-internal ((((name . "Emacs Commands history") (candidates . #f(compiled-function () #<bytecode 0x1ffd35a88d85>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal state" ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert state" ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert normal) s...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) (20 . helm-toggle-resplit-and-swap-windows) (C-tab . undefined) (67108897 . helm-toggle-suspend-update) (3 keymap ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (67108987 . helm-enlarge-window) (67108989 . helm-narrow-window) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keeping se...") (must-match . t) (group . helm-command) (match-dynamic . t)) ((name . "Emacs Commands") (candidates . #f(compiled-function () #<bytecode 0x1ffd3626ae55>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal state" ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert state" ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert normal) s...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) (20 . helm-toggle-resplit-and-swap-windows) (C-tab . undefined) (67108897 . helm-toggle-suspend-update) (3 keymap ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (67108987 . helm-enlarge-window) (67108989 . helm-narrow-window) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keeping se...") (must-match . t) (group . helm-command) (match-dynamic . t))) nil "M-x " nil nil "*helm M-x*" nil nil helm-M-x-input-history))
  helm((((name . "Emacs Commands history") (candidates . #f(compiled-function () #<bytecode 0x1ffd35a88d85>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal stat..." ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert stat..." ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert nor...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keep...") (must-match . t) (group . helm-command) (match-dynamic . t)) ((name . "Emacs Commands") (candidates . #f(compiled-function () #<bytecode 0x1ffd3626ae55>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal stat..." ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert stat..." ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert nor...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keep...") (must-match . t) (group . helm-command) (match-dynamic . t))) nil "M-x " nil nil "*helm M-x*" nil nil helm-M-x-input-history)
  apply(helm ((((name . "Emacs Commands history") (candidates . #f(compiled-function () #<bytecode 0x1ffd35a88d85>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal state" ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert state" ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert normal) s...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) (20 . helm-toggle-resplit-and-swap-windows) (C-tab . undefined) (67108897 . helm-toggle-suspend-update) (3 keymap ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (67108987 . helm-enlarge-window) (67108989 . helm-narrow-window) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keeping se...") (must-match . t) (group . helm-command) (match-dynamic . t)) ((name . "Emacs Commands") (candidates . #f(compiled-function () #<bytecode 0x1ffd3626ae55>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal state" ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert state" ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert normal) s...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) (20 . helm-toggle-resplit-and-swap-windows) (C-tab . undefined) (67108897 . helm-toggle-suspend-update) (3 keymap ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (67108987 . helm-enlarge-window) (67108989 . helm-narrow-window) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keeping se...") (must-match . t) (group . helm-command) (match-dynamic . t))) nil "M-x " nil nil "*helm M-x*" nil nil helm-M-x-input-history))
  helm(:sources (((name . "Emacs Commands history") (candidates . #f(compiled-function () #<bytecode 0x1ffd35a88d85>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal stat..." ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert stat..." ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert nor...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keep...") (must-match . t) (group . helm-command) (match-dynamic . t)) ((name . "Emacs Commands") (candidates . #f(compiled-function () #<bytecode 0x1ffd3626ae55>)) (keymap keymap (keymap ...) keymap (21 . helm-M-x-universal-argument) keymap (127 . delete-backward-char) (27 keymap ...) (C-return . helm-cr-empty-string) keymap (tab . helm-execute-persistent-action) (normal-state keymap "Auxiliary keymap for Normal stat..." ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...) (insert-state keymap "Auxiliary keymap for Insert stat..." ... ... ... ... ... ... ... ...) (\(insert\ normal\)-state keymap "Auxiliary keymap for (insert nor...") (26 . helm-select-action) (f13 lambda nil ... ...) (f12 lambda nil ... ...) (f11 lambda nil ... ...) (f10 lambda nil ... ...) (f9 lambda nil ... ...) (f8 lambda nil ... ...) (f7 lambda nil ... ...) (f6 lambda nil ... ...) (f5 lambda nil ... ...) (f4 lambda nil ... ...) (f3 lambda nil ... ...) (f2 lambda nil ... ...) (menu-bar keymap ...) (help keymap ...) (23 . #f(compiled-function () ... #<bytecode 0x1ffd3929591d>)) (f1 lambda nil ... ...) (8 keymap ... ... ... ... ...) ...) (action . helm-type-command-actions) (persistent-action . helm-M-x-persistent-action) (persistent-help . "Describe this command") (help-message . helm-M-x-help-message) (requires-pattern . 0) (filtered-candidate-transformer helm-M-x-transformer-no-sort helm-fuzzy-highlight-matches) (volatile . t) (match . identity) (redisplay . identity) (nomark . t) (coerce . helm-symbolify) (header-line . "C-j: Describe this command (keep...") (must-match . t) (group . helm-command) (match-dynamic . t))) :prompt "M-x " :buffer "*helm M-x*" :history helm-M-x-input-history)
  helm-M-x-read-extended-command([okr LaTeX-length-list ansi-color-apply-overlay-face epg-context-signers reftex-untie-multifile-symbols 0 rng-what-schema vc-git-stash-snapshot TeX-command-Biber reftex-default-bibliography pdf-cache-renderpage-highlight pdf-cache-pagelinks semantic-tag-write-list-slot-value markdown-match-bold evil-replace-alist LaTeX-item-tabular* helm-type-timers-actions biblio--selection-insert template nsm-permanent-host-settings doom-modeline-eldoc-bar mixal gnus-summary-recenter ob-ipython--create-repl cl-print--preprocess semantic--tag-unlink-list-from-buffer org-fragtog-ignore-predicates ellipses wicon vc-git-conflicted-files 0 TeX-auto-local semanticdb-project-database-file-child-p evil-visual-exchange-corners Load\ snippets\.\.\. \\prime sp-message test-command container \' ---5 helm-grep-mode-jump-other-window-forward org-ref-notes-directory ---8 sessions evil-collection-js2-mode-setup \. define-mode-local-override evil-replace-state-local-map \\bullet ...])
  helm-M-x(nil)
  funcall-interactively(helm-M-x nil)
  call-interactively(helm-M-x nil nil)
  command-execute(helm-M-x)


------
Marvin M. Doyley Ph.D.  
Professor of Electrical and Computer Engineering,
Professor of Biomedical Engineering, and of Imaging Sciences,
University of Rochester
518 Computer Science Building Rochester NY 14627 
Tel: 585-275-3774 Fax: 585-273-4919
Website: http://www.ece.rochester.edu/projects/doyley_lab/