--text follows this line--

Emacs -Q
;; the following script hopefully will demonstrate the issue
;; after evaluating the code below, url-retrieve seems started a new
;; process to do the https call, that call should give a bad request with
;; json response {"error":"invalid_client"}
;; but it took a lot of time for the call back to be called
;; I suspect sth special about Xero domain’s certificate which caused
;; this issue. https://www.google.com.au is fine
;; tried starting with emacs option, --no-init
(setq url-debug t)

(defun http-handle-response (status method &optional url bufname raw
stay-in-window)
  "Switch to the buffer returned by `url-retreive'.
The buffer contains the raw HTTP response sent by the server."
  (message (format "%s" raw)))

(display-buffer
 (let* ((url "https://identity.xero.com/connect/post")
        (method "POST"))
   (url-retrieve url 'http-handle-response (append (list method url (format
"*HTTP %s %s*" method url)) '())))
 t)

;; the following curl command will return response very quickly
curl -X POST https://identity.xero.com/connect/token -H 'Authorization:
Basic  abc' -H 'Content-Type: application/x-www-form-urlencoded'
--data-urlencode 'abc=def'

Response: {"error":"invalid_client"}



In GNU Emacs 27.2 (build 1, x86_64-apple-darwin18.7.0, NS appkit-1671.60
Version 10.14.6 (Build 18G95))
 of 2021-03-28 built on builder10-14.porkrind.org
Windowing system distributor 'Apple', version 10.3.2022
System Description:  macOS 11.4

Recent messages:
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 'configure --with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-modules'

Configured features:
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Memory information:
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