BiometricPrompt Executor and/or callback was null

Question

I'm using BiometricPrompt from androidx.biometric:biometric:1.0.0-beta02 for the authenticate process. But i face very strange problem.

First time i call biometricsPromt.authenticate() everything works fine, the library shows me the screen depending what security method is set(pattern,fingerprint, password and etc…) then the callback is called and everything is good.

The problem is when i call biometricsPromt.authenticate() for the second time i got the error:

E/DeviceCredentialHandler: onCreate: Executor and/or callback was null!

I'm passing executor and callback of course -> they are not null

Does anyone face the same problem or have some idea what can be the problem?

This is how i'm creating the BiometricPromt

`

companion object {
        private val executor: Executor by lazy {
            Executors.newSingleThreadExecutor()
        }

        fun showBiometricsPrompt(
            activity: FragmentActivity,
            callback: BiometricPrompt.AuthenticationCallback
        ): BiometricPrompt {
            val promptInfo = BiometricPrompt.PromptInfo.Builder()
                .setTitle(activity.getString(R.string.title_authentication))
                .setDescription(activity.getString(R.string.msg_authenticate_first))
                .setDeviceCredentialAllowed(true)
                .build()

            val biometricPrompt =
                BiometricPrompt(
                    activity,
                    executor, callback
                )
            biometricPrompt.authenticate(promptInfo)
            return biometricPrompt
        }

`

And here is how i called:

`

BiometricsHelper.showBiometricsPrompt(
                this,
                object : BiometricPrompt.AuthenticationCallback() {
                    override fun onAuthenticationError(errorCode: Int, errString: CharSequence) {
                        super.onAuthenticationError(errorCode, errString)

                        showToastMsg(errString.toString())
                    }

                    override fun onAuthenticationFailed() {
                        super.onAuthenticationFailed()
                    }

                    override fun onAuthenticationSucceeded(result: BiometricPrompt.AuthenticationResult) {
                        super.onAuthenticationSucceeded(result)

                    }
                })

`

I am having this exact same issue in a legacy app, in a fragment. Did you only manage to fix it by finishing the activity? — NightStalker, Nov 27 '19 at 08:32

score 1 · Answer 1 · answered Oct 16 '19 at 17:59

1

Here's a work around this problem, but not a complete fix.

You need to call recreate() after you finish doing whatever you set out to do after the authentication.

This will restart the activity and allow the biometric prompt to be shown again.

answered Oct 16 '19 at 17:59

Vansh Arora

392
2
13

score 1 · Answer 2 · answered Nov 27 '19 at 08:45

1

It seems it is related to this line: .setDeviceCredentialAllowed(true)

If I change that to false, it works every time without re-creating the activity

answered Nov 27 '19 at 08:45

NightStalker

113
3
11

Yes, but if you want to use it should re-create the activity – Kostadin Georgiev Dec 16 '19 at 09:13
Yes buggy as always, they seem to be ignoring that flag when recreating the BiometricPrompt object. – David Jan 31 '20 at 13:12

score 0 · Answer 3 · answered Oct 17 '19 at 03:21

0

What device are you testing on? Can you file a bug on the public issuetracker here with both

adb bugreport foo.zip
ideally a .zip of a sample app that reproduces the issue?

answered Oct 17 '19 at 03:21

Kevin

168
11

score 0 · Answer 4 · answered Jun 17 '20 at 13:00

0

Remove:

private val executor: Executor by lazy {
    Executors.newSingleThreadExecutor()
}

and replace your executor with:

ContextCompat.getMainExecutor(activity)

answered Jun 17 '20 at 13:00

Haider Malik

1,581
1
20
23

BiometricPrompt Executor and/or callback was null

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