ARTICLE AD BOX
🔐 Firebase Phone OTP Issue in Closed Testing – Need Expert Guidance
Hi everyone,
I’m facing a very confusing issue with Firebase Phone Authentication (OTP) in a production build during closed testing, and I’d really appreciate guidance from experienced Android / Firebase engineers.
📌 Problem Summary
Firebase Phone Auth is integrated correctly
OTP is successfully sent to testers’ phone numbers
However:
On testers’ devices + their own numbers → OTP verification fails with “OTP expired”
On same tester device + my phone number → OTP verifies successfully
On my device + tester number → OTP also verifies successfully
So:
❌ Issue is not device-specific
❌ Issue is not number-specific
❌ Issue is not code logic related (same build, same flow)
🔍 Observations
In some cases, reCAPTCHA does not appear for testers
When My Number → reCAPTCHA appears → OTP works
When Testers Number → reCAPTCHA doesn’t appear→ OTP expires
App is uploaded via Play Store Closed Testing
Firebase Console → Phone Auth enabled
SHA-1 / SHA-256 configured
Tried:
Auto verification
Forced reCAPTCHA
Clearing sessions
Resend OTP
Fresh installs
🤔 Key Questions
Is this related to Firebase trust / Play Integrity / SafetyNet?
Does closed testing behave differently than production rollout for Phone Auth?
Is there any Firebase-side configuration that must be enabled for testers?
Has anyone faced OTP working only for owner numbers but not for testers?
At this point, the behavior feels Firebase-side, not app-side.
If you’ve handled Firebase Auth at scale or during Play Store rollout,
your insights would be extremely valuable 🙏
Thanks in advance!
