Update time: Jan 17, 2025
Some people may encounter gtm.js failed to load and displayed 404, for example:
There are several reasons:
No Released Version
If it is a newly installed GTM, no released version has been released yet, gtm.js will be 404
Solution：just publish a version on GTM.
Browser Plug-in Blocking
There is a browser plugin blocking gtm.js, eg:
Solution : check the plugins on the browser or remove them
Content Security Policy（CSP）
CSP blocks GTM requests.
Check in the browser developer tools and will see a CSP error.
Solution : Add the following code to the header of all pages:
<meta http-equiv="Content-Security-Policy" content="default-src 'self'; script-src 'self' www.googletagmanager.com www.google-analytics.com; connect-src 'self' www.google-analytics.com; img-src 'self' data: www.googletagmanager.com www.google-analytics.com; style-src 'self'; frame-src 'self' www.googletagmanager.com">
Wrong Container ID
The wrong container ID causes the page to fail to load, so 404 is displayed.
If my GTM container ID is GTM-PHXQ69M, but I installed GTM-PHXQ69M1, 404 will be displayed, such as:
Solution: Check whether the container ID is correct
Browser cache or DNS issues
Browser’s cache or DNS records may be preventing you from accessing the latest or correct GTM scripts.
Solution ：Try clearing your browser cache or flushing your DNS.
Container Code Incorrectly Placed
If not placed correctly, it may cause the script to not load as expected.
Solution： GTM Container code must be placed within the <head> tag or at the very top of the <body> tag.
