Unencoded Spaces Breaking UTM Tracking: Fix in 60 Seconds

Your GA4 campaign name shows up as "spring" instead of "spring sale 2024."

You check the URL. Unencoded spaces. Parameters truncated at the first space.

Here's the 60-second fix.

The Problem

❌ BROKEN:
?utm_campaign=spring sale 2024
              ↑     ↑
         Space breaks parsing

GA4 shows: "spring"
Missing: " sale 2024"

Spaces in URLs are illegal. Browsers and analytics platforms parse them as parameter terminators.

Why It Happens

URLs cannot contain unencoded spaces. When you include them:

1. Browser truncates parameter at first space
2. GA4 receives incomplete value
3. Remaining text is ignored or misinterpreted
4. Campaign names fragment across reports

Real Example

Company: SaaS startup Campaign: "black friday sale" Budget: $8,000 Google Ads URL: ?utm_campaign=black friday sale

Result in GA4:

• Campaign name: "black"
• Expected: "black friday sale"

Impact:

• Could not identify which "black" campaign performed best
• All Black Friday variations merged under incomplete name
• $8,000 spend with corrupted attribution

60-second fix prevented this.

The Fix

Option 1: URL Encode (Recommended)

❌ BEFORE:
?utm_campaign=spring sale 2024

✅ AFTER:
?utm_campaign=spring%20sale%202024
              ↑   ↑    ↑   ↑
         Each space → %20

Result in GA4: "spring sale 2024" (exactly as intended)

Option 2: Use Underscores

❌ BEFORE:
?utm_campaign=spring sale 2024

✅ AFTER:
?utm_campaign=spring_sale_2024
              ↑   ↑    ↑
         Spaces → underscores

Result in GA4: "spring_sale_2024" (readable, no encoding)

Option 3: Use Hyphens

❌ BEFORE:
?utm_campaign=spring sale 2024

✅ AFTER:
?utm_campaign=spring-sale-2024
              ↑    ↑    ↑
         Spaces → hyphens

Result in GA4: "spring-sale-2024" (readable, SEO-friendly)

Option 4: Remove Spaces

❌ BEFORE:
?utm_campaign=spring sale 2024

✅ AFTER:
?utm_campaign=springsale2024

Result in GA4: "springsale2024" (compact, less readable)

Quick Encoding Script

// Encode UTM parameter value
function encodeUtmValue(value) {
    return encodeURIComponent(value);
}
 
// Usage
const campaign = "spring sale 2024";
const encoded = encodeUtmValue(campaign);
console.log(encoded);
// Output: spring%20sale%202024
 
// Build full URL
const url = `https://site.com?utm_campaign=${encoded}`;
console.log(url);
// https://site.com?utm_campaign=spring%20sale%202024

Advanced: Build Complete Campaign URL

function buildCampaignUrl(base, utms) {
    const params = new URLSearchParams();
 
    // Auto-encodes all values including spaces
    params.set('utm_source', utms.source);
    params.set('utm_medium', utms.medium);
    params.set('utm_campaign', utms.campaign);
 
    if (utms.content) params.set('utm_content', utms.content);
    if (utms.term) params.set('utm_term', utms.term);
 
    return `${base}?${params.toString()}`;
}
 
// Usage
const campaignUrl = buildCampaignUrl('https://site.com', {
    source: 'google ads',
    medium: 'paid search',
    campaign: 'spring sale 2024'
});
 
console.log(campaignUrl);
// https://site.com?utm_source=google+ads&utm_medium=paid+search&utm_campaign=spring+sale+2024
// Note: URLSearchParams encodes spaces as + (valid alternative to %20)

How Browsers Handle Spaces

Input URL:
https://site.com?utm_campaign=spring sale

Browser interpretation:
https://site.com?utm_campaign=spring
                                    ↑
                            Stops parsing here

Everything after space:
" sale" → Ignored or treated as separate parameter

Technical Explanation:

RFC 3986 (URL standard) defines spaces as reserved characters. Browsers must either:

1. Truncate at the space (most common)
2. Auto-encode the space (inconsistent across browsers)
3. Reject the URL entirely (rare)

GA4 only receives what the browser sends, which is often the truncated value.

Platform Behavior

Prevention Rules

Rule 1: Always Encode Values

// ✅ CORRECT
const params = {
    utm_source: 'facebook',
    utm_campaign: 'spring sale'
};
 
const queryString = new URLSearchParams(params).toString();
// Automatically encodes: utm_campaign=spring+sale
// (Note: + is valid encoding for spaces in query strings)

Rule 2: Use Consistent Naming Convention

✅ RECOMMENDED:
utm_campaign=spring_sale_2024  (underscores)
utm_campaign=spring-sale-2024  (hyphens)
utm_campaign=springsale2024    (no separators)

❌ AVOID:
utm_campaign=spring sale 2024  (spaces - must encode)

Rule 3: Validate Before Launch

function hasUnencodedSpaces(url) {
    const queryString = url.split('?')[1] || '';
    return queryString.includes(' ');
}
 
// Usage
const url = 'site.com?utm_campaign=spring sale';
if (hasUnencodedSpaces(url)) {
    console.error('❌ URL contains unencoded spaces!');
    // Fix automatically
    const fixed = url.replace(/ /g, '%20');
    console.log('✅ Fixed:', fixed);
}

Testing Process

Step 1: Build URL with Encoding (30 seconds)

const baseUrl = 'https://site.com';
const params = {
    utm_source: 'google',
    utm_medium: 'cpc',
    utm_campaign: 'spring sale 2024'
};
 
const url = `${baseUrl}?${new URLSearchParams(params).toString()}`;
console.log(url);
// https://site.com?utm_source=google&utm_medium=cpc&utm_campaign=spring+sale+2024

Step 2: Test in GA4 Real-Time (30 seconds)

1. Click URL
2. Open GA4 → Realtime
3. Check campaign name
4. Verify complete value appears

Bulk Fix Script (Python)

import urllib.parse
 
def fix_unencoded_spaces(urls):
    fixed_urls = []
 
    for url in urls:
        # Split URL into base and query
        if '?' in url:
            base, query = url.split('?', 1)
 
            # Parse query parameters
            params = urllib.parse.parse_qs(query)
 
            # Rebuild with proper encoding
            encoded_params = urllib.parse.urlencode(params, doseq=True)
 
            fixed_url = f"{base}?{encoded_params}"
            fixed_urls.append(fixed_url)
        else:
            fixed_urls.append(url)
 
    return fixed_urls
 
# Usage
urls = [
    "site.com?utm_campaign=spring sale 2024",
    "site.com?utm_source=google ads&utm_medium=paid search"
]
 
fixed = fix_unencoded_spaces(urls)
for url in fixed:
    print(url)

Common Mistakes

Mistake 1: Partial Encoding

❌ WRONG:
?utm_campaign=spring%20sale 2024
              ↑         ↑     ↑
         Encoded    Space! (breaks parsing)

✅ RIGHT:
?utm_campaign=spring%20sale%202024

Mistake 2: Manual Copy-Paste

User copies:   "spring sale 2024"
Pastes into:   URL builder field
Builder adds:  ?utm_campaign=spring sale 2024
Result:        Broken (if builder doesn't auto-encode)

✅ FIX: Use builder with auto-encoding

Mistake 3: Spreadsheet Formula Errors

❌ WRONG Excel formula:
=A1&"?utm_campaign="&B1

If B1 = "spring sale", produces:
site.com?utm_campaign=spring sale (broken)

✅ RIGHT:
=A1&"?utm_campaign="&SUBSTITUTE(B1," ","_")

Produces:
site.com?utm_campaign=spring_sale (works)

Real-World Example: Email Campaign

Platform: Mailchimp Campaign: Black Friday 2024 Subject Line: "Black Friday Exclusive Sale"

Template merge tag:

<a href="{{website}}?utm_campaign={{campaign_name}}">Shop Now</a>

Variables:

website = https://shop.com
campaign_name = Black Friday Sale

Result (BROKEN):

https://shop.com?utm_campaign=Black Friday Sale

GA4 received:

• Campaign: "Black" (truncated)

Fix the template:

<a href="{{website}}?utm_campaign={{campaign_name|urlencode}}">Shop Now</a>

Or manually encode campaign_name:

campaign_name = Black_Friday_Sale

Result (FIXED):

https://shop.com?utm_campaign=Black_Friday_Sale

GA4 received:

• Campaign: "Black_Friday_Sale" (complete)

FAQ

Should I use %20 or + for spaces?

Both are valid. %20 works everywhere. + is valid in query strings but can be less reliable. Use %20 for consistency.

What if spaces are already in my live URLs?

Fix immediately. Update all placements. Consider 301 redirects from broken to fixed URLs to preserve any external links.

Do URL builders automatically encode spaces?

Most do, but not all. Always check the final URL before launch. Google Campaign URL Builder encodes automatically, but custom builders may not.

Can I use tabs or newlines?

No. Encode all whitespace: space → %20, tab → %09, newline → %0A. Never include literal whitespace in URLs.

Will this affect my historical data?

No. Historical data remains fragmented. The fix only affects future traffic from corrected URLs.

How do I find all URLs with unencoded spaces?

Export your campaign URLs to a spreadsheet, then use this formula to detect spaces:

=IF(ISNUMBER(FIND(" ",A1)),"Contains space","OK")

What about spaces in the domain or path?

Domain names cannot have spaces (invalid DNS). Path spaces should be encoded as %20 or replaced with hyphens for SEO-friendly URLs.

Can email clients fix this automatically?

Some email clients auto-encode URLs, but behavior is inconsistent. Never rely on auto-encoding—always encode manually before sending.

Does this affect mobile vs desktop differently?

No. Both mobile and desktop browsers follow the same URL encoding rules. Unencoded spaces break tracking on all devices.

What other characters need encoding?

Common characters requiring encoding: # → %23, & → %26, = → %3D, ? → %3F, / → %2F (when used in parameter values, not URL structure).

Conclusion

Unencoded spaces break UTM tracking. Fix: Replace spaces with %20 or underscores.

❌ utm_campaign=spring sale
✅ utm_campaign=spring%20sale
✅ utm_campaign=spring_sale

60 seconds to fix. Perfect tracking restored.

Technical Reference: URL Encoding Issues Validation Rule