Hope this helps:

Debugger entered--Lisp error: (wrong-type-argument plistp "")
plist-put("" DAV:status 404)
url-dav-process-response(#<killed buffer> "https://remoteserver.net/remote.php/dav/calendars/user/some-calendar-3/")
(let ((resultbuf (org-caldav-url-retrieve-synchronously url "PROPFIND" request-data extra)) (retr 1)) (while (and (= 0 (buffer-size resultbuf)) (< retr org-caldav-retry-attempts)) (org-caldav-debug-print 1 (format "org-caldav-url-dav-get-properties: could not get data from url: %s\n trying again..." url)) (setq resultbuf (org-caldav-url-retrieve-synchronously url "PROPFIND" request-data extra)) (setq retr (1+ retr))) (org-caldav-namespace-bug-workaround resultbuf) (url-dav-process-response resultbuf url))
(let ((request-data (concat "<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n" "<DAV:propfind xmlns:DAV='DAV:'>\n<DAV:prop>" "<DAV:" property "/></DAV:prop></DAV:propfind>\n")) (extra (quote (("Depth" . "1") ("Content-type" . "text/xml"))))) (let ((resultbuf (org-caldav-url-retrieve-synchronously url "PROPFIND" request-data extra)) (retr 1)) (while (and (= 0 (buffer-size resultbuf)) (< retr org-caldav-retry-attempts)) (org-caldav-debug-print 1 (format "org-caldav-url-dav-get-properties: could not get data from url: %s\n trying again..." url)) (setq resultbuf (org-caldav-url-retrieve-synchronously url "PROPFIND" request-data extra)) (setq retr (1+ retr))) (org-caldav-namespace-bug-workaround resultbuf) (url-dav-process-response resultbuf url)))
org-caldav-url-dav-get-properties("https://remoteserver.net/remote.php/dav/calendars/user/some-calendar-3/" "resourcetype")
(let* ((output (org-caldav-url-dav-get-properties (org-caldav-events-url) "resourcetype")) (status (plist-get (cdr (car output)) (quote DAV:status)))) (if (or (= (/ status 100) 2) (= status 404)) nil (org-caldav-debug-print 1 "Got error status from PROPFIND: " output) (error "Could not query CalDAV URL %s." (org-caldav-events-url))) (if (= status 404) (progn (org-caldav-debug-print 1 "Got 404 status - assuming calendar is new and empty.") (setq org-caldav-empty-calendar t)) (if (= (length output) 1) (progn (org-caldav-debug-print 1 "This is an empty calendar. Setting flag.") (setq org-caldav-empty-calendar t)))) t)
org-caldav-check-connection()
(if (= numretry (1- org-caldav-retry-attempts)) (org-caldav-check-connection) (org-caldav-debug-print 1 "Got error while checking connection (will try again):" err) (setq numretry (1+ numretry)))
(condition-case err (progn (org-caldav-check-connection) (setq success t)) (error (if (= numretry (1- org-caldav-retry-attempts)) (org-caldav-check-connection) (org-caldav-debug-print 1 "Got error while checking connection (will try again):" err) (setq numretry (1+ numretry)))))
(while (null success) (condition-case err (progn (org-caldav-check-connection) (setq success t)) (error (if (= numretry (1- org-caldav-retry-attempts)) (org-caldav-check-connection) (org-caldav-debug-print 1 "Got error while checking connection (will try again):" err) (setq numretry (1+ numretry))))))
(let ((numretry 0) success) (while (null success) (condition-case err (progn (org-caldav-check-connection) (setq success t)) (error (if (= numretry (1- org-caldav-retry-attempts)) (org-caldav-check-connection) (org-caldav-debug-print 1 "Got error while checking connection (will try again):" err) (setq numretry (1+ numretry)))))))
(lambda nil (let ((--dolist-tail-- (append org-caldav-files (list (org-caldav-inbox-file org-caldav-inbox)))) filename) (while --dolist-tail-- (setq filename (car --dolist-tail--)) (if (not (file-exists-p filename)) (progn (user-error "File %s does not exist" filename))) (setq --dolist-tail-- (cdr --dolist-tail--)))) (if (org-caldav-use-oauth2) (progn (org-caldav-check-oauth2 org-caldav-url) (org-caldav-retrieve-oauth2-token org-caldav-url org-caldav-calendar-id))) (let ((numretry 0) success) (while (null success) (condition-case err (progn (org-caldav-check-connection) (setq success t)) (error (if (= numretry (1- org-caldav-retry-attempts)) (org-caldav-check-connection) (org-caldav-debug-print 1 "Got error while checking connection (will try again):" err) (setq numretry (1+ numretry))))))) (if resume nil (setq org-caldav-ics-buffer (org-caldav-generate-ics)) (setq org-caldav-event-list nil org-caldav-previous-files nil) (org-caldav-load-sync-state) (if org-caldav-previous-files (progn (let ((missing (cl-set-difference org-caldav-previous-files org-caldav-files :test ...))) (if (and missing (not ...)) (progn (user-error "Sync aborted")))))) (let ((--dolist-tail-- org-caldav-event-list) cur) (while --dolist-tail-- (setq cur (car --dolist-tail--)) (org-caldav-event-set-status cur nil) (setq --dolist-tail-- (cdr --dolist-tail--)))) (org-caldav-update-eventdb-from-org org-caldav-ics-buffer) (org-caldav-update-eventdb-from-cal)) (org-caldav-update-events-in-cal org-caldav-ics-buffer) (org-caldav-update-events-in-org) (org-caldav-save-sync-state) (setq org-caldav-event-list nil) (save-current-buffer (set-buffer org-caldav-ics-buffer) (set-buffer-modified-p nil) (kill-buffer)) (delete-file (buffer-file-name org-caldav-ics-buffer)))()
funcall((lambda nil (let ((--dolist-tail-- (append org-caldav-files (list (org-caldav-inbox-file org-caldav-inbox)))) filename) (while --dolist-tail-- (setq filename (car --dolist-tail--)) (if (not (file-exists-p filename)) (progn (user-error "File %s does not exist" filename))) (setq --dolist-tail-- (cdr --dolist-tail--)))) (if (org-caldav-use-oauth2) (progn (org-caldav-check-oauth2 org-caldav-url) (org-caldav-retrieve-oauth2-token org-caldav-url org-caldav-calendar-id))) (let ((numretry 0) success) (while (null success) (condition-case err (progn (org-caldav-check-connection) (setq success t)) (error (if (= numretry ...) (org-caldav-check-connection) (org-caldav-debug-print 1 "Got error while checking connection (will try again):" err) (setq numretry ...)))))) (if resume nil (setq org-caldav-ics-buffer (org-caldav-generate-ics)) (setq org-caldav-event-list nil org-caldav-previous-files nil) (org-caldav-load-sync-state) (if org-caldav-previous-files (progn (let ((missing ...)) (if (and missing ...) (progn ...))))) (let ((--dolist-tail-- org-caldav-event-list) cur) (while --dolist-tail-- (setq cur (car --dolist-tail--)) (org-caldav-event-set-status cur nil) (setq --dolist-tail-- (cdr --dolist-tail--)))) (org-caldav-update-eventdb-from-org org-caldav-ics-buffer) (org-caldav-update-eventdb-from-cal)) (org-caldav-update-events-in-cal org-caldav-ics-buffer) (org-caldav-update-events-in-org) (org-caldav-save-sync-state) (setq org-caldav-event-list nil) (save-current-buffer (set-buffer org-caldav-ics-buffer) (set-buffer-modified-p nil) (kill-buffer)) (delete-file (buffer-file-name org-caldav-ics-buffer))))
(let ((org-caldav-inbox (quote "~/Documents/Calendars/some-calendar-3-inbox.org")) (org-caldav-files (quote ("~/Documents/Calendars/some-calendar-3.org"))) (org-caldav-calendar-id (quote "some-calendar-3"))) (funcall (quote (lambda nil (let ((--dolist-tail-- (append org-caldav-files ...)) filename) (while --dolist-tail-- (setq filename (car --dolist-tail--)) (if (not ...) (progn ...)) (setq --dolist-tail-- (cdr --dolist-tail--)))) (if (org-caldav-use-oauth2) (progn (org-caldav-check-oauth2 org-caldav-url) (org-caldav-retrieve-oauth2-token org-caldav-url org-caldav-calendar-id))) (let ((numretry 0) success) (while (null success) (condition-case err (progn ... ...) (error ...)))) (if resume nil (setq org-caldav-ics-buffer (org-caldav-generate-ics)) (setq org-caldav-event-list nil org-caldav-previous-files nil) (org-caldav-load-sync-state) (if org-caldav-previous-files (progn (let ... ...))) (let ((--dolist-tail-- org-caldav-event-list) cur) (while --dolist-tail-- (setq cur ...) (org-caldav-event-set-status cur nil) (setq --dolist-tail-- ...))) (org-caldav-update-eventdb-from-org org-caldav-ics-buffer) (org-caldav-update-eventdb-from-cal)) (org-caldav-update-events-in-cal org-caldav-ics-buffer) (org-caldav-update-events-in-org) (org-caldav-save-sync-state) (setq org-caldav-event-list nil) (save-current-buffer (set-buffer org-caldav-ics-buffer) (set-buffer-modified-p nil) (kill-buffer)) (delete-file (buffer-file-name org-caldav-ics-buffer))))))
eval((let ((org-caldav-inbox (quote "~/Documents/Calendars/some-calendar-3-inbox.org")) (org-caldav-files (quote ("~/Documents/Calendars/some-calendar-3.org"))) (org-caldav-calendar-id (quote "some-calendar-3"))) (funcall (quote (lambda nil (let ((--dolist-tail-- ...) filename) (while --dolist-tail-- (setq filename ...) (if ... ...) (setq --dolist-tail-- ...))) (if (org-caldav-use-oauth2) (progn (org-caldav-check-oauth2 org-caldav-url) (org-caldav-retrieve-oauth2-token org-caldav-url org-caldav-calendar-id))) (let ((numretry 0) success) (while (null success) (condition-case err ... ...))) (if resume nil (setq org-caldav-ics-buffer (org-caldav-generate-ics)) (setq org-caldav-event-list nil org-caldav-previous-files nil) (org-caldav-load-sync-state) (if org-caldav-previous-files (progn ...)) (let (... cur) (while --dolist-tail-- ... ... ...)) (org-caldav-update-eventdb-from-org org-caldav-ics-buffer) (org-caldav-update-eventdb-from-cal)) (org-caldav-update-events-in-cal org-caldav-ics-buffer) (org-caldav-update-events-in-org) (org-caldav-save-sync-state) (setq org-caldav-event-list nil) (save-current-buffer (set-buffer org-caldav-ics-buffer) (set-buffer-modified-p nil) (kill-buffer)) (delete-file (buffer-file-name org-caldav-ics-buffer)))))))
(let* ((syms (mapcar (quote org-caldav-var-for-key) calkeys)) (vals calvalues) (body (function (lambda nil (let ((--dolist-tail-- ...) filename) (while --dolist-tail-- (setq filename ...) (if ... ...) (setq --dolist-tail-- ...))) (if (org-caldav-use-oauth2) (progn (org-caldav-check-oauth2 org-caldav-url) (org-caldav-retrieve-oauth2-token org-caldav-url org-caldav-calendar-id))) (let ((numretry 0) success) (while (null success) (condition-case err ... ...))) (if resume nil (setq org-caldav-ics-buffer (org-caldav-generate-ics)) (setq org-caldav-event-list nil org-caldav-previous-files nil) (org-caldav-load-sync-state) (if org-caldav-previous-files (progn ...)) (let (... cur) (while --dolist-tail-- ... ... ...)) (org-caldav-update-eventdb-from-org org-caldav-ics-buffer) (org-caldav-update-eventdb-from-cal)) (org-caldav-update-events-in-cal org-caldav-ics-buffer) (org-caldav-update-events-in-org) (org-caldav-save-sync-state) (setq org-caldav-event-list nil) (save-current-buffer (set-buffer org-caldav-ics-buffer) (set-buffer-modified-p nil) (kill-buffer)) (delete-file (buffer-file-name org-caldav-ics-buffer))))) (binds nil)) (while syms (setq binds (cons (list (car-safe (prog1 syms (setq syms ...))) (list (quote quote) (car-safe (prog1 vals ...)))) binds))) (eval (list (quote let) binds (list (quote funcall) (list (quote quote) body)))))
(progn (let* ((syms (mapcar (quote org-caldav-var-for-key) calkeys)) (vals calvalues) (body (function (lambda nil (let (... filename) (while --dolist-tail-- ... ... ...)) (if (org-caldav-use-oauth2) (progn ... ...)) (let (... success) (while ... ...)) (if resume nil (setq org-caldav-ics-buffer ...) (setq org-caldav-event-list nil org-caldav-previous-files nil) (org-caldav-load-sync-state) (if org-caldav-previous-files ...) (let ... ...) (org-caldav-update-eventdb-from-org org-caldav-ics-buffer) (org-caldav-update-eventdb-from-cal)) (org-caldav-update-events-in-cal org-caldav-ics-buffer) (org-caldav-update-events-in-org) (org-caldav-save-sync-state) (setq org-caldav-event-list nil) (save-current-buffer (set-buffer org-caldav-ics-buffer) (set-buffer-modified-p nil) (kill-buffer)) (delete-file (buffer-file-name org-caldav-ics-buffer))))) (binds nil)) (while syms (setq binds (cons (list (car-safe (prog1 syms ...)) (list (quote quote) (car-safe ...))) binds))) (eval (list (quote let) binds (list (quote funcall) (list (quote quote) body))))))
(let (calkeys calvalues oauth-enable) (let ((--dolist-tail-- (number-sequence 0 (1- (length calendar)) 2)) i) (while --dolist-tail-- (setq i (car --dolist-tail--)) (setq calkeys (append calkeys (list (nth i calendar))) calvalues (append calvalues (list (nth (1+ i) calendar)))) (setq --dolist-tail-- (cdr --dolist-tail--)))) (progn (let* ((syms (mapcar (quote org-caldav-var-for-key) calkeys)) (vals calvalues) (body (function (lambda nil (let ... ...) (if ... ...) (let ... ...) (if resume nil ... ... ... ... ... ... ...) (org-caldav-update-events-in-cal org-caldav-ics-buffer) (org-caldav-update-events-in-org) (org-caldav-save-sync-state) (setq org-caldav-event-list nil) (save-current-buffer ... ... ...) (delete-file ...)))) (binds nil)) (while syms (setq binds (cons (list (car-safe ...) (list ... ...)) binds))) (eval (list (quote let) binds (list (quote funcall) (list (quote quote) body)))))))
org-caldav-sync-calendar((:calendar-id "some-calendar-3" :files ("~/Documents/Calendars/some-calendar-3.org") :inbox "~/Documents/Calendars/some-calendar-3-inbox.org"))
(while --dolist-tail-- (setq calendar (car --dolist-tail--)) (org-caldav-debug-print 1 "Syncing first calendar entry:" calendar) (org-caldav-sync-calendar calendar) (setq --dolist-tail-- (cdr --dolist-tail--)))
(let ((--dolist-tail-- org-caldav-calendars) calendar) (while --dolist-tail-- (setq calendar (car --dolist-tail--)) (org-caldav-debug-print 1 "Syncing first calendar entry:" calendar) (org-caldav-sync-calendar calendar) (setq --dolist-tail-- (cdr --dolist-tail--))))
(if (null org-caldav-calendars) (org-caldav-sync-calendar) (let ((--dolist-tail-- org-caldav-calendars) calendar) (while --dolist-tail-- (setq calendar (car --dolist-tail--)) (org-caldav-debug-print 1 "Syncing first calendar entry:" calendar) (org-caldav-sync-calendar calendar) (setq --dolist-tail-- (cdr --dolist-tail--)))))
(if (and org-caldav-event-list (not (eq org-caldav-resume-aborted (quote never))) (or (eq org-caldav-resume-aborted (quote always)) (and (eq org-caldav-resume-aborted (quote ask))) (y-or-n-p "Last sync seems to have been aborted. Should I try to resume? "))) (org-caldav-sync-calendar org-caldav-previous-calendar t) (setq org-caldav-sync-result nil) (if (null org-caldav-calendars) (org-caldav-sync-calendar) (let ((--dolist-tail-- org-caldav-calendars) calendar) (while --dolist-tail-- (setq calendar (car --dolist-tail--)) (org-caldav-debug-print 1 "Syncing first calendar entry:" calendar) (org-caldav-sync-calendar calendar) (setq --dolist-tail-- (cdr --dolist-tail--))))))
org-caldav-sync()
funcall-interactively(org-caldav-sync)
call-interactively(org-caldav-sync record nil)
command-execute(org-caldav-sync record)
execute-extended-command(nil "org-caldav-sync")
smex-read-and-run(("org-caldav-sync" "eval-buffer" "customize" "help" "customize-group" "customize-set-variable" "report-emacs-bug" "org2web-publish" "org-beamer-export-to-pdf" "org-latex-export-to-pdf" "org-beamer-select-environment" "helm-bibtex" "rectangle-mark-mode" "org-web-tools-insert-link-for-url" "org-board-open" "org-open-at-point" "cfw:open-org-calendar" "org-schedule" "org-publish-project" "paradox-list-packages" "count-words" "org-board-new" "org-insert-link" "org-store-link" "org-deadline" "org-web-tools-insert-web-page-as-entry" "org-table-kill-row" "magit-diff" "annotate-mode" "org-publish-current-project" "org-web-tools-archive-attach" "calendar" "org-table-insert-column" "ispell-word" "org-table-delete-column" "paradox-upgrade-packages" "org-table-hline-and-move" "org-toggle-inline-images" "org-ref" "org-agenda" "org-date-from-calendar" "org-clone-subtree-with-time-shift" "swiper" "org-web-tools-archive-view" "rename-file" "notmuch" "magit-commit" "list-packages" "org-table-insert-row" "org-web-tools-read-url-as-org" ...))
smex()
funcall-interactively(smex)
call-interactively(smex nil nil)
command-execute(smex)

-------- Mensagem Original --------
Ligado 2/11/2019, 17:55, Lars Ingebrigtsen escreveu:

> Nuno Pedrosa <info@nunopedrosa.net> writes:
>
>> Getting the following error while syncing a list of calendars with a
>> remote Nextcloud server.
>>
>> This bug was also reported in the org-caldav repository, by several of
>> its users: https://github.com/dengste/org-caldav/issues/189
>>
>> Looks like an issue with url-dav.
>
> Could you (setq debug-on-error t), repeat the bug and post the resulting
> backtrace?
>
> --
> (domestic pets only, the antidote for overdose, milk.)
> bloggy blog: http://lars.ingebrigtsen.no