When Invisible UX Breaks Trust: A Klarna Payment Flow Case Study
How a seemingly small UX oversight in a payment verification process nearly cost a conversion — and what we can learn from it.
⚡TL;DR
🔍 The Problem
- •Klarna's phone verification silently failed without proper error feedback
- •No guidance on required international phone number format (+33, +39, etc.)
- •Multiple failed attempts with no clear resolution path
💡 Key Lessons
- •Never let systems fail silently in critical flows
- •Provide clear input guidance and real-time validation
- •Test with real-world international use cases
Bottom line: Small UX oversights in payment flows can cost significant conversions. Simple fixes like placeholder text and proper error messages could have prevented this entire issue.
The Problem in Action
Here's exactly what I encountered during the Klarna verification process. Notice the lack of guidance and feedback:
Step 1: Phone Number Entry
Simple input field with no indication of required international format
Step 2: The Silent Failure
Waiting forever for an SMS that will never arrive, with no error message
⚠️ This is where the user journey broke down completely. No guidance, no feedback, no resolution.
Picture this: You've found the perfect product online, added it to your cart, and you're ready to checkout. You choose Klarna as your payment method — a trusted, familiar option. But then something goes wrong. Not dramatically wrong, just... quietly wrong. And that's where the real problem begins.
01The Story: What Actually Happened
🛒 The Setup
I was making a purchase on a third-party e-commerce site. Everything was going smoothly until I reached the payment step. I selected Klarna — a payment service I've used before and trust. The checkout process redirected me to Klarna's payment window for verification.
Typical e-commerce checkout with multiple payment options
📱 The Phone Verification Step
Klarna asked me to verify my phone number — a standard security measure. I saw a simple input field asking for my phone number. No big deal, right? I entered my number and clicked "Continue."
The interface accepted my input and moved me to the next screen, where I was supposed to enter the OTP (One-Time Password) that would be sent to my phone.
❌ The actual Klarna interface: Simple input field with no format guidance
⚠️ The Silent Failure
I waited. And waited. No OTP arrived. No error message appeared. No indication that anything was wrong. The interface just sat there, patiently waiting for me to enter a code that would never come.
"This is where most users would start feeling frustrated and confused. Was it my phone? The network? The service?"
⚠️ The endless wait: OTP screen with no feedback when SMS never arrives
02The Frustration: Multiple Failed Attempts
Attempt 1
Tried with my French number
Attempt 2
Switched to my Italian number
Attempt 3
Tried "Resend Code" multiple times
🤔 The User's Mental Model
Here's what was going through my head during each attempt:
- •"Maybe the network is slow? Let me wait a bit longer..."
- •"Perhaps my French number isn't recognized? Let me try my Italian one..."
- •"The 'Resend Code' button works, so the system thinks it's sending something..."
- •"Am I doing something wrong? Is this service broken?"
03The Root Cause: What Was Really Wrong
💡 The Revelation
The issue wasn't with my phone numbers or the network. The problem was that I wasn't entering the phone numbers in the correct international format. Klarna's system expected numbers with proper country codes (like +33 for France or +39 for Italy), but the interface gave me no indication of this requirement.
❌ What I Entered
Numbers without country codes
✅ What Was Expected
Proper international format
The difference between local and international phone number formats
04The UX Problems: Where Klarna Failed
🚫 Missing Guidance
- ×No placeholder text showing the expected format
- ×No country code selector or dropdown
- ×No visual cues about international formatting
🔇 Silent Failures
- ×No validation feedback on incorrect format
- ×No error messages when SMS sending fails
- ×System allows progression despite invalid input
🎯 The Core UX Principle Violated
"Users should never have to guess what format is expected, and systems should never fail silently. Good UX means preventing errors before they happen, not hiding them after they occur."
05The Business Impact: Why This Matters
💰 The Cost of Poor UX in Payment Flows
Abandoned Carts
Users give up when they can't complete payment
Lost Trust
Frustrating experiences damage brand reputation
Reduced Conversions
Each failed attempt decreases likelihood of purchase
Poor UX in payment flows directly impacts business metrics and conversion rates
🔍 The Hidden Problem
Most users don't complain when they encounter UX issues — they simply leave. This makes it harder for companies to identify and fix these problems. How many potential customers has Klarna lost to this issue without even knowing it?
06The Solutions: Quick Wins That Make a Difference
✅ Clear Input Guidance
Add placeholder text showing the expected format:
✅ Country Selection
Add a country code dropdown or flag selector:
✅ Real-time Validation
Validate input before allowing progression:
✅ Clear Error Messages
Show specific feedback when SMS fails:
Before vs After: Visual Comparison
❌ Current (Problematic) Design
✅ Improved Design
🚀 Implementation Priority
These are not complex features requiring months of development. They're simple UX improvements that could be implemented in a few hours and would immediately improve user experience and conversion rates.
07Key Takeaways for Product Teams
🔍 Test with Real-World Scenarios
Don't just test with ideal inputs. Test with international users, different number formats, and edge cases that real users encounter.
🛡️ Design for Failure
Assume things will go wrong and design clear paths for recovery. Silent failures are worse than obvious errors because they leave users confused and frustrated.
💡 Guide, Don't Guess
Never make users guess what format is expected. Use placeholders, examples, and real-time validation to guide them toward success.
⚡ Small Details, Big Impact
In payment flows, every friction point matters. A small UX issue can cost thousands in lost conversions, especially when users can't complete their purchase.
💬 Let's Discuss
Have you encountered similar silent failures in payment flows? How does your team handle error states in critical user journeys?
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Visual representations and data formatting in this case study were enhanced with the assistance of Claude AI.