Server-side Google Tag Manager has an excellent Preview mode, which lets you inspect incoming requests, monitor the event data object, view console messages, and identify outgoing requests, among other things. To enable this Preview mode on the web, you simply need to click the Preview button in the container, after which any requests sent from the same browser instance will be automatically shown in the Preview mode window. However, what about if you want to send requests from another browser?
Sometimes, in Google Tag Manager’s Debug mode, you’ll see tags appear with the status Still Running, and you’ll (eventually) notice that these tags are not doing what they are supposed to be doing. When you see this message on a tag, it technically means this: The tag failed to signal Google Tag Manager that it is “done”. The technical explanation is, naturally, too simple to be useful. In this article, I’ll explore what “done” means, and how especially Google Analytics tags manifest this behavior.