Why are my UTM parameters not being recognized correctly in GA4?

GA4 usually ignores or splits UTM parameters because they are lost on a redirect before the Google tag reads the URL, are spelled inconsistently, or use a utm_medium that matches no channel rule. GA4 reads the campaign parameters from the URL of the page where the session starts. If they are no longer in the URL at that moment, or if their values do not follow a consistent pattern, the campaign appears as a different source, as “(not set)” or under “Unassigned”.

Also check whether you are looking at the right dimension. UTMs from a later visit show up in session-scoped dimensions such as Session source / medium, but not in First user source, which keeps the source of the user’s first visit.

Why does GA4 not recognise my UTM parameters?

• Redirects remove the parameters. A redirect from http to https, from the domain without www to the one with www, or to a page with a trailing slash can drop the query string. When the page loads, the UTMs are gone.
• Inconsistent spelling. UTM values are case-sensitive. According to Google, “Meta” and “meta” or “SpringSale” and “Spring_Sale” are treated as different values, which splits one campaign into several rows.
• Medium does not fit the channel groups. GA4 assigns sessions to channels based on source and medium. A medium such as newsletter instead of email or paid-social without a matching rule often ends up as “Unassigned”.
• Required parameters are missing. Google recommends always using utm_source, utm_medium and utm_campaign together. Some parameters, such as utm_creative_format and utm_marketing_tactic, are not reported in GA4 at all.
• Consent and tag timing. If the Google tag only fires after consent and the visitor first moves to another page, the landing URL with the UTMs may never be measured.
• Payment providers and self-referrals. A visitor returning from a payment provider or a second own domain can show up as a new referral. Add such domains to the list of unwanted referrals in the web data stream.
• UTMs on Google Ads links. If auto-tagging is active, the GCLID already carries the campaign information. Google warns that combining manual campaign values with a GCLID can lead to misattribution.

How do I find the cause?

1. Click your own campaign link and check the address bar after the page has loaded. If the UTMs are missing, a redirect is removing them.
2. Check the redirect chain in the browser’s developer tools under Network. Every redirect must pass the full query string on.
3. Use DebugView or Tag Assistant and check that the page_view event contains the full URL with UTMs in page_location.
4. Open the Traffic acquisition report with the dimension Session source / medium and look for variants of the same campaign with different spelling.
5. Compare with the default channel group rules. If your campaign lands in “Unassigned”, compare your utm_medium with the values Google expects for each channel.

How do I set up UTMs correctly?

• Agree on a naming convention. One source per platform, one medium per channel, everything in lowercase.
• Use mediums that match the channels, for example email for newsletters or cpc for paid clicks, unless you work with custom channel groups.
• Link to the final URL, exactly as it loads, so that no redirect is needed.
• Leave Google Ads to auto-tagging and use UTMs for all other campaigns.
• Use a URL builder such as Google’s Campaign URL Builder instead of typing parameters by hand.

You can also build consistent campaign links with our UTM generator.

Link campaigns directly to the final URL, write all UTM values in lowercase and choose a utm_medium that matches a default channel. Then test each link once in DebugView before the campaign goes live.

Sources

• Analytics Help: Collect campaign data with custom URLs
• Analytics Help: Default channel group
• Analytics Help: Scopes of traffic-source dimensions
• Analytics Help: Identify unwanted referrals

Want every campaign to show up correctly in GA4? We check your tagging, redirects, consent setup and channel rules and set up a UTM convention that holds. Book a free intro call or read more about our tracking services.