September 25, 2019
Multiple installations of Google Tag Manager detected by Tag Assistant: What to do?
“Multiple installations of Google Tag Manager” – says Tag Assistant. This is a fairly common “issue” noticed in online communities. The reason why I surrounded the word issue with quotation marks is that usually, this warning is no issue at all.
Here’s what I’m talking about:
What looks really concerning in the screenshot above is the fact that the same container is added multiple times to the same page. At least Google Tag Assistant says so. But you’re probably pretty sure that the GTM container is added only once. So what the heck?
What is going on?
So if you’re seeing a message that Multiple installations of Google Tag Manager are detected and their IDs are actually the same, I have a hunch that you’re working on a Single Page Application.
If yes, then most likely, there is nothing to worry about (but just to double-check, continue reading).
Unfortunately, Google Tag Assistant is quite buggy when it comes to debugging Single Page Applications. Even though only one GTM container is installed, Tag Assistant may display multiple container instances as the app loads or a visitor continues to browse. This does not happen on ALL single-page applications but is quite often nonetheless.
What should you do?
To verify whether you actually have multiple installations of Google Tag Manager, check network requests in browser’s developer tools. In this demo (and as always), I’ll be using Google Chrome.
In the top right corner, click 3 dots, then go to More tools > Developer Tools.
Switch to Network tab and in the search field enter “gtm.js” (without quotation marks), keep All selected, and refresh the page.
After the page has reloaded, take a look at how many gtm.js do you see?
If one, you’re good to go. Just ignore Tag Assistant’s warning about multiple installations.
If on the other hand, you see multiple gtm.js, this means that there certainly are multiple GTM container snippets loaded on a page. Is that expected? Was it intended to have multiple containers on the same page?
Have a discussion about that with someone who might know the project/website you’re currently working on. Even though it isn’t optimal to use multiple GTM containers, it is possible. You can learn more about this here.
If nobody intended to have multiple containers on the same site, just remove one that shouldn’t be there (or ask someone to do that).
Multiple installations of Google Tag Manager – Final words
To sum up, if you see this error in Google Tag Assistant and you’re working on a single page application, most likely this error is just a Tag Assistant’s bug. For some reason, the extension doesn’t play very well with SPAs.
To make sure that the website is indeed using just a single GTM container, check requests in browser’s developer tools.