Why Google Analytics Shows PANTHEON_STRIPPED in UTM Parameters (And How to Fix It)

The Mystery: PANTHEON_STRIPPED Appearing in Your Analytics

You’re running a successful digital marketing campaign, carefully tracking UTM parameters, when you notice something strange in Google Analytics: instead of your clean utm_source=google parameters, you’re seeing PANTHEON_STRIPPED scattered throughout your reports.

Common scenarios we hear from clients:

“For our landing page submissions, most of them have ‘Pantheon stripped’ noted. We want to ensure those are being attributed properly – can you help determine why those are displaying that way in Gravity Forms?”

~ Confused WordPress developer

“Google Analytics is showing PANTHEON_STRIPPED in the utm_source URL parameter. What’s going on with our campaign tracking?”

~ Frustrated Digital Marketer

If you’re hosting on Pantheon and seeing this issue, you’re not alone. This isn’t a bug – it’s actually Pantheon’s edge caching system doing exactly what it’s designed to do, but interfering with your marketing attribution.

What Is PANTHEON_STRIPPED?

PANTHEON_STRIPPED is Pantheon’s way of handling UTM parameters for caching efficiency.

Pantheon automatically processes URLs with UTM parameters (utm_source, utm_medium, utm_campaign, etc.) through its “stripping logic” to normalize URLs for better caching performance. While this improves site speed, it can break marketing attribution tracking.

Why Pantheon does this:

• Improved caching: Multiple URLs with different UTM parameters would create separate cache entries
• Better performance: Fewer cache variations mean faster page loads
• Reduced server load: Less processing needed for parameter variations

The trade-off: Your marketing attribution gets muddy when parameters are stripped.

How PANTHEON_STRIPPED Breaks Your Marketing Data

Scenario 1: WordPress Plugin Data Collection

The problem: Gravity Forms (or other plugins like Monster Insights) showing “PANTHEON_STRIPPED” instead of actual UTM values.

What happens:

1. First visit: User arrives with utm_source=google&utm_medium=cpc
2. Pantheon processing: URL gets normalized for caching
3. Plugin data collection: Gravity Forms reads the current URL to populate hidden fields
4. Result: Instead of “google”, the form captures “PANTHEON_STRIPPED”

Real example:

Original URL: https://yoursite.com/contact/?utm_source=google&utm_medium=cpc

Cached URL:   https://yoursite.com/contact/?utm_source=PANTHEON_STRIPPED

Form Data:    Source = "PANTHEON_STRIPPED" instead of "google"

Scenario 2: Google Analytics Attribution

The problem: GA4 reports showing PANTHEON_STRIPPED in campaign reports.

What happens:

1. Marketing campaign: Ads point to URLs with UTM parameters
2. 301 PHP redirects: Old URLs redirect to new pages, carrying UTM parameters through
3. Pantheon processing: UTM parameters get stripped during redirect
4. Analytics tracking: GA4 receives PANTHEON_STRIPPED instead of original values

Real example:

Ad URL:        https://yoursite.com/contact/?utm_source=google&utm_campaign=hosting_demo

Redirect:      301 to https://yoursite.com/contact-us/

Final URL:     https://yoursite.com/contact-us/?utm_source=PANTHEON_STRIPPED

GA4 Data:      Campaign = "PANTHEON_STRIPPED"

Common Causes and Solutions

Cause 1: Outdated Marketing URLs with Redirects

The situation: Your ads still point to old URLs that redirect to new pages.

Example scenario:

• Current page: /contact-us/
• Old page: /contact/ (redirects to /contact-us/)
• Ad URLs: Still pointing to /contact/?utm_source=google
• Result: UTM parameters get stripped during a PHP redirect process

Solution: Update Your Marketing URLs

1. Audit all campaign URLs in Google Ads, Facebook Ads, email campaigns
2. Update to point directly to current pages (no redirects)
3. Test new URLs to ensure UTM parameters pass through correctly

Before:

https://yoursite.com/contact/?utm_source=google&utm_medium=cpc

After:

https://yoursite.com/contact-us/?utm_source=google&utm_medium=cpc

Cause 2: Plugin Parameter Capture Timing

The situation: WordPress plugins capturing UTM data after Pantheon has processed the URL.

Solution: Capture UTM Parameters with JavaScript

Instead of relying on server-side URL reading, capture parameters client-side before they’re processed:

javascript

// Add this to your website to capture original UTM parameters
function getOriginalUTMParameters() {
    const urlParams = new URLSearchParams(window.location.search);
    return {
        utm_source: urlParams.get('utm_source'),
        utm_medium: urlParams.get('utm_medium'),
        utm_campaign: urlParams.get('utm_campaign'),
        utm_term: urlParams.get('utm_term'),
        utm_content: urlParams.get('utm_content')
    };
}

// Store in sessionStorage for form population
const utmParams = getOriginalUTMParameters();
if (utmParams.utm_source) {
    sessionStorage.setItem('original_utm_source', utmParams.utm_source);
}

Cause 3: Overloading UTM Parameter Namespace

The situation: Using UTM parameters for purposes other than marketing attribution.

What not to do:

https://yoursite.com/page/?utm_source=internal_navigation
https://yoursite.com/page/?utm_medium=menu_click

Solution: Use custom parameters for non-marketing tracking:

https://yoursite.com/page/?nav_source=internal&click_type=menu

Preventing PANTHEON_STRIPPED Issues

Best Practice 1: Direct URL Targeting

Always point marketing campaigns directly to final destinations:

• ✅ https://yoursite.com/current-page/?utm_source=google
• ❌ https://yoursite.com/old-page/?utm_source=google (that redirects)

Best Practice 2: UTM Parameter Validation

Test your campaign URLs before launching:

1. Visit the URL directly in an incognito browser
2. Check the final URL in the address bar
3. Verify UTM parameters are still intact
4. Test form submissions to ensure correct data capture

Best Practice 3: Alternative Attribution Methods

For critical attribution, don’t rely solely on UTM parameters:

Google Tag Manager approach:

javascript

// Capture and store UTM parameters on page load
window.dataLayer = window.dataLayer || [];
window.dataLayer.push({
  'event': 'utm_capture',
  'utm_source': getURLParameter('utm_source'),
  'utm_medium': getURLParameter('utm_medium'),
  'utm_campaign': getURLParameter('utm_campaign')
});

Hidden form fields approach:

html

<!-- Populate these with JavaScript, not server-side URL reading -->
<input type="hidden" name="utm_source" id="utm_source" value="">
<input type="hidden" name="utm_medium" id="utm_medium" value="">

Testing Your UTM Attribution

Test 1: Direct URL Test

1. Create a test URL with UTM parameters
2. Visit in incognito mode to avoid cache
3. Check the final URL – do parameters remain intact?
4. Submit a test form – are correct values captured?

Test 2: Campaign Flow Test

1. Use actual ad URLs from your campaigns
2. Follow the complete user journey (click ad → land on page → submit form)
3. Check both GA4 and form data for correct attribution
4. Test on mobile and desktop

Test 3: Redirect Chain Test

1. Identify any redirects in your campaign URLs
2. Trace the full redirect chain using tools like Redirect Checker
3. Test UTM parameter preservation through each redirect
4. Update URLs to eliminate unnecessary redirects

When to Contact Pantheon Support

Pantheon support can help with:

• Unusual caching behavior affecting your specific site
• Configuration issues with edge cache settings
• Questions about cookie handling (related to UTM storage)

What they typically can’t change:

• The fundamental PANTHEON_STRIPPED behavior (it’s by design)
• UTM parameter handling for caching optimization
• Site-specific marketing attribution requirements

Professional Marketing Attribution Setup

While this tutorial covers the most common PANTHEON_STRIPPED issues, complex marketing attribution often requires professional implementation:

Advanced attribution scenarios:

• Multi-domain campaign tracking with proper cross-domain setup
• Complex funnel attribution across multiple touchpoints
• Integration with CRM systems for complete customer journey tracking
• Custom attribution models for B2B sales cycles

When to get professional help:

• Multiple marketing channels requiring unified attribution
• Complex redirect chains from legacy URLs
• Integration between marketing platforms and WordPress/CRM systems
• Advanced Google Analytics 4 and Google Tag Manager configurations

What’s included in professional marketing attribution setup:

• Complete campaign URL audit and optimization
• Custom JavaScript solutions for parameter capture
• Google Tag Manager configuration for reliable attribution
• Testing and validation across all marketing channels
• Documentation and team training on best practices

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Dealing with complex marketing attribution issues on Pantheon or other hosting platforms?  Contact Knihter for professional digital marketing implementation and website optimization services. We specialize in solving technical marketing challenges and ensuring accurate campaign attribution.

Related Services:

• Marketing attribution setup and optimization
• Google Analytics 4 and GTM implementation
• Pantheon hosting optimization and configuration
• Campaign URL strategy and redirect management