Why is there “Unassigned” traffic in GA4?

Short answer

“Unassigned” traffic in Google Analytics 4 (GA4) generally occurs when the platform is unable to attribute user activity to a specific source, media or campaign due to reasons such as configuration errors, incorrect use of UTM parameters, inappropriate redirects, or issues with the implementation of tags and triggers.

In other words, Google Analytics 4 will display “Unassigned” when it does not have the necessary information to attribute the measured events to a specific traffic channel.

How to fix it

There is no single solution to this problem. You should probably try one or more of the solutions listed here.

Check your UTMs, sources and means of traffic

The most common reason lies in Google Analytics’ inability to assign a specific source and media combination to a specific channel. GA4 always assigns a source and media combination to a specific channel according to the official documentation.

For example, if we had as source and medium the value: “facebook / paid” GA4 will automatically assign it to the “Paid Social” channel. But if instead we had “ebook / activation” this traffic will be in the “Unassigned” channel.

This means that any source and media combination that cannot be assigned to a channel according to the official documentation will always be registered as “Unassigned”. Therefore it is always recommended to follow the standard parameters mentioned in the documentation or create a custom channel to add all those source and media combinations that Google does not assign to a channel.

Unassigned when the source and medium say “(not set)”.

In the case of having the value “(not set)” among the sources and media belonging to the “Unassigned” channel, the solution will be more complex. Here we list the possible options

1. You are using the Measurement Protocol incorrectly: you are sending events outside the 72 hours enabled and without a timestamp value or without indicating necessary values such as the client_id. This could be causing the problem.
2. Your GA4 tag is activating before the Google Tag: Some users have experienced this problem and solve it by delaying the activation of the GA4 tag and speeding up the activation of the Google Tag. For example: Activate the Google Tag in the “page view” and the GA4 tag in the “DOM Ready”.
3. An external tool sends data to GA4: It is known that technologies such as Segment could be sending additional data to GA4 through the Measurement Protocol and could be the cause of the problem.
4. Audience triggers: Custom audience triggers or predictive audiences in GA4 are known to cause this problem. There is also no known solution for this particular casuistry.
5. Incomplete or misspelled UTM parameters: In this case we recommend our article Campaign traffic measured by UTMs are not visible in GA4 acquisition report to understand best practices regarding UTM parameters.
6. The data has not yet been processed by GA4: This is related to GA4 processing times. The solution is to simply wait 24 to 48 hours. This is explained in detail within the article Why do events appear only in GA4’s “real-time” report?.
7. Your sessions are not triggering the “session_start” event: This is easy to recognize by performing a debug process using the Google Tag Assistant. It is very common to find this problem when the GA4 tag is misconfigured in Google Tag Manager, an incorrect Server-side tagging configuration is being used.