What This Rule Detects

Browsers NEVER send URL fragments (anything after #) to servers. When # appears before ?, all UTM parameters are completely invisible to GA4. This causes 100% tracking failure.

Why It Matters

Business Impact:

• 100% attribution loss for affected traffic
• Campaigns show as Direct traffic
• Impossible to measure ROI
• Ad spend attribution fails completely

Technical Impact:

• Browser behavior: Only sends URL up to # character
• GA4 receives: example.com/page# (query string stripped)
• Result: Zero UTM data captured

Common Scenarios

Scenario 1: Single Page Apps (SPA)

Many React/Vue apps use hash routing:

Scenario 2: Anchor Links with UTMs

Marketing emails with jump links:

Scenario 3: Accidental Hash Placement

Copy-paste errors or CMS issues:

How to Fix

Step 1: Identify Affected URLs

1. Check your campaign URLs in:

   • Email templates
   • Social media posts
   • Ad platforms
   • QR codes / printed materials

2. Search for pattern: # before ?

Step 2: Reorder URL Structure

Correct Order: domain + path + ? query + # fragment

Step 3: Verify in GA4

1. GA4 → Reports → Acquisition → Traffic acquisition
2. Check if campaigns now appear
3. Verify Source/Medium attribution

Examples

❌ Incorrect Examples

https://example.com#top?utm_source=facebook&utm_medium=cpc
Result: GA4 sees only https://example.com#top
Tracking: FAILS (100% data loss)

✅ Correct Examples

https://example.com?utm_source=facebook&utm_medium=cpc#top
Result: GA4 receives all UTM parameters
Tracking: SUCCESS (attributed to Facebook CPC)

GA4 Impact Analysis

Channel Grouping:

• Affected traffic: Appears as "Direct" channel
• Lost attribution: 100% of sessions with this pattern

Session Attribution:

• First-click: Lost (defaults to Direct)
• Last-click: Lost
• Multi-touch: Missing from attribution path

Related Validation Rules

External Resources

• Google Analytics 4: Campaign URL Builder
• GA4 Documentation: Collect Campaign Data
• URL Structure Specification (W3C)