1. What exactly did you do?

   I try to use the low-high estimates with the column attribute {est+}
   as documented in http://orgmode.org/manual/Column-attributes.html.

   For that, I tried to assign low and high effort values as in
   http://thread.gmane.org/gmane.emacs.orgmode/93505/focus=93514.  The
   formats I tried:

   :Effort: +4.0-12.0
   :Effort: 4.0-12.0
   :Effort: 4-12
   :Effort: 4:00-12:00
   :Effort: 4:00-1.5d
   :Effort_Low: 4:00
   :Effort_High: 1.5d

2. What did you expect to happen?

   In the attached estplus.org, when I do `M-x org-columns', I expected
   to see the column view with the value for {est+}.

3. What happened instead?

   In the attached estplus.org, when I do `M-x org-columns', I get the
   error 'Invalid duration format'.

   I attach the backtrace as well.

Automatically generated with `org-submit-bug-report'

Emacs  : GNU Emacs 27.0.50 (build 2, x86_64-pc-linux-gnu, GTK+ Version 3.22.11)
 of 2017-11-06
Package: Org mode version 9.1.3 (9.1.3-elpa @ /home/francisv/.emacs.d/elpa/org-20171116/)

current state:
==============
(setq
 org-src-mode-hook '(org-src-babel-configure-edit-buffer org-src-mode-configure-edit-buffer)
 org-after-todo-state-change-hook '(org-clock-out-if-current)
 org-metadown-hook '(org-babel-pop-to-session-maybe)
 org-clock-out-hook '(org-clock-remove-empty-clock-drawer)
 org-mode-hook '((closure
                  (org-inlinetask-min-level buffer-face-mode-face org-struct-menu org-last-state org-id-track-globally
                   org-clock-start-time texmathp-why remember-data-file org-agenda-tags-todo-honor-ignore-options iswitchb-temp-buflist
                   calc-embedded-open-mode calc-embedded-open-formula calc-embedded-close-formula align-mode-rules-list
                   org-export-registered-backends ffap-url-regexp t)
                  nil (add-hook (quote change-major-mode-hook) (quote org-show-block-all) (quote append) (quote local)))
                 (closure (*this* org-babel-confirm-evaluate-answer-no t) nil
                  (add-hook (quote change-major-mode-hook) (quote org-babel-show-result-all) (quote append) (quote local)))
                 #[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-show-block-all append local] 5]
                 #[0 "\300\301\302\303\304$\207" [add-hook change-major-mode-hook org-babel-show-result-all append local] 5]
                 org-babel-result-hide-spec org-babel-hide-all-hashes)
 org-archive-hook '(org-attach-archive-delete-maybe)
 org-confirm-elisp-link-function 'yes-or-no-p
 org-agenda-before-write-hook '(org-agenda-add-entry-text)
 org-metaup-hook '(org-babel-load-in-session-maybe)
 org-bibtex-headline-format-function '(closure (org-id-locations org-agenda-search-view-always-boolean org-agenda-overriding-header t)
                                       (entry) (cdr (assq :title entry)))
 org-babel-pre-tangle-hook '(save-buffer)
 org-tab-first-hook '(org-babel-hide-result-toggle-maybe org-babel-header-arg-expand)
 org-occur-hook '(org-first-headline-recenter)
 org-cycle-hook '(org-cycle-hide-archived-subtrees org-cycle-hide-drawers org-cycle-show-empty-lines
                  org-optimize-window-after-visibility-change)
 org-speed-command-hook '(org-speed-command-activate org-babel-speed-command-activate)
 org-confirm-shell-link-function 'yes-or-no-p
 org-link-parameters '(("id" :follow org-id-open) ("rmail" :follow org-rmail-open :store org-rmail-store-link)
		       ("mhe" :follow org-mhe-open :store org-mhe-store-link) ("irc" :follow org-irc-visit :store org-irc-store-link)
		       ("info" :follow org-info-open :export org-info-export :store org-info-store-link)
		       ("gnus" :follow org-gnus-open :store org-gnus-store-link)
		       ("docview" :follow org-docview-open :export org-docview-export :store org-docview-store-link)
		       ("bibtex" :follow org-bibtex-open :store org-bibtex-store-link)
		       ("bbdb" :follow org-bbdb-open :export org-bbdb-export :complete org-bbdb-complete-link :store org-bbdb-store-link)
		       ("w3m" :store org-w3m-store-link) ("file+sys") ("file+emacs") ("doi" :follow org--open-doi-link)
		       ("elisp" :follow org--open-elisp-link) ("file" :complete org-file-complete-link)
		       ("ftp" :follow (lambda (path) (browse-url (concat "ftp:" path)))) ("help" :follow org--open-help-link)
		       ("http" :follow (lambda (path) (browse-url (concat "http:" path))))
		       ("https" :follow (lambda (path) (browse-url (concat "https:" path))))
		       ("mailto" :follow (lambda (path) (browse-url (concat "mailto:" path))))
		       ("news" :follow (lambda (path) (browse-url (concat "news:" path)))) ("shell" :follow org--open-shell-link))
 )

--
Francisco Velázquez