How We Survived Passkeys: Lessons Learned

When our team first committed to replacing password-based auth with passkeys in Q3 2023, we thought the hardest part would be implementing FIDO2 and WebAuthn standards. We were wrong. Six months later, after a bumpy rollout, 92% user adoption, and zero credential stuffing breaches, we’ve compiled the hard-won lessons that kept our passkey migration from collapsing.

Lesson 1: Never Rush the Rollout

Our first mistake was setting a 6-week deadline for full passkey enforcement. We skipped phased rollouts, pushing passkeys to all 50k+ users at once. The result? A 300% spike in support tickets in the first 48 hours, mostly from users on legacy devices that didn’t support hardware-backed passkeys.

We quickly pivoted to a 3-phase rollout: first internal employees, then beta users, then general audience. This gave us time to fix edge cases, like Safari’s initial lack of support for cross-device passkey syncing, before they hit mainstream users.

Lesson 2: User Education Beats Technical Jargon

We initially sent emails explaining “FIDO2-compliant public key cryptography” to users. Open rates were 12%, and most users who tried to set up passkeys gave up at the first “Allow this site to create a passkey?” prompt.

We rewrote all messaging to focus on user benefits: “Sign in with your face/fingerprint instead of passwords. No more reset links.” We added in-app tooltips, 30-second explainer videos, and a dedicated help center section with step-by-step screenshots for iOS, Android, Windows, and macOS. Support tickets dropped 70% overnight.

Lesson 3: Fallback Methods Are Not Optional

Passkeys are resilient, but they’re not infallible. We had users lose access to their only passkey-enabled device, or travel to regions where their primary device’s biometric auth was blocked. We learned the hard way that removing all password fallbacks immediately is a recipe for churn.

We implemented a tiered fallback system: users can add up to 3 backup passkeys (e.g., a hardware security key, a secondary phone), and we kept password auth as a last resort for 6 months post-rollout, only disabling it for users who explicitly opted out. This reduced account lockout rates by 85%.

Lesson 4: Test Across Every Device and Browser

We tested passkeys on Chrome and Safari on macOS, assuming that was enough. We missed Firefox’s initial buggy implementation of WebAuthn for cross-device passkeys, and Android 10 devices that didn’t support the required SafetyNet APIs. These gaps led to hundreds of users being unable to sign in at all.

We built a dedicated test matrix covering 20+ browser/OS combinations, including legacy systems, and added automated regression tests for passkey flows. We also partnered with FIDO Alliance’s testing lab to validate our implementation against latest standards.

Lesson 5: Track the Right Metrics

We initially measured success by “number of passkeys created,” which looked great on dashboards. But we missed critical metrics: passkey sign-in success rate (we had a 22% failure rate for first-time users), fallback usage rate, and support ticket categorization for passkey issues.

We built a custom dashboard tracking 12 passkey-specific metrics, including time-to-sign-in, cross-device passkey sync success, and biometric auth failure rates by device model. This let us fix issues like a bug in our iOS implementation that caused passkeys to fail for users with iCloud Keychain disabled.

Conclusion

Passkeys are the future of authentication, but they’re not a “set it and forget it” upgrade. Our rollout nearly failed because we prioritized technical compliance over user experience and phased testing. By slowing down, educating users, and building robust fallbacks, we turned a potential disaster into a 92% adoption rate and a 100% reduction in credential stuffing attacks. If you’re planning a passkey rollout, learn from our mistakes: your users (and support team) will thank you.