GTM URL has changed, please update the default options
The new URL for GTM is: https://www.googletagmanager.com/gtag/js and the previous URL throws a 404 error
URL mới cho GTM là: https://www.googletagmanager.com/gtag/js và URL trước đó gây ra lỗi 404
thanks
Perhaps Google changed something, but the old URL still works for me:
% curl -s https://www.googletagmanager.com/gtm.js?id=GTM-XXXXXXX
// Copyright 2012 Google Inc. All rights reserved.
(function(){
var data = {
"resource": {
"version":"1",
"macros":[{
"function":"__u",
The new URL referred to above also works.
Anyone have more information on this, yet the m/gtm.js? seems to give 400 , but seems to still work.
Should I change my url to the gtag/js?

Where are you? Does it work if you just use curl? Are you sure you're using the right GTM ID?
I note that if I don't use a GTM ID I get a 400 error:
% curl -I https://www.googletagmanager.com/gtm.js
HTTP/2 400
but if I use a valid ID it works (status 200):
% curl -I https://www.googletagmanager.com/gtm.js?id=GTM-TDWXYZW
HTTP/2 200