How to check for live issues with google tag manager?

user_67167 0
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Previously working code that downloads a csv file from our site, now fails. Chrome, Safari and Edge don't display anything helpful except "Blob Blocked", but Firefox shows a stack trace;

Uncaught TypeError: Location.href setter: Access to 'blob:http://oursite.test/7e283bab-e48c-a942-928c-fae0907fdc82' from script denied.

Then a stack dump from googletagmanager

This appears to be a fault in the tagmanager code introduced in the last couple of weeks.

The fault appears in all browsers and is resolved immediately by commenting out the tag manager. The problem reported by a customer on the production system, and then found on both staging and locally. The customer advised they had used the export function successfully 2 weeks ago.

The question really is, do Google maintain a public facing issues log for things like the tag manager?

google-tag-manager
2 Answers

It's not about GTM as a library really, it's about poor user implementation. It's not up to Google to check for user-introduced conflicts with the rest of the site's functionality.

What you could do is go to GTM, and see what has been released in the past two weeks. Inspect things and look for anything that could interfere with the site's functionality. At the same time - do the opposite, see all the front-end changes introduced during this time frame by the web-dev team.

Things to watch for is mostly unclosured JS deployed in custom HTML tags. junior GTM implementation specialists like to use the global space, taking the global variables, often after the page is loaded, thus overwriting front-end's variables.

Sometimes, people would deploy minified unclosured code to the DOM, thus chaotically taking short var names. To the same end.

This is likely the easiest and most common way for GTM to break front-end. There definitely still are many ways to do so besides this though.

If this doesn't help, there's another easy way to debug it: make a new workspace from Default (or whatever is live), go into the preview mode and confirm that the issue still happens. Now start disabling newest created fired tags one by one and pinpoint which one causes the issue.

Let us know what it was.

user_37009930

Solution was to replace the previous tag manager code with the latest recommended snippet

user_671670
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