Remote Config fetch fails below API 19 (Kitkat)

Describe your environment

• Android Studio version: 3.5.1
• Firebase Component: Remote Config (Database, Firestore, Storage, Functions, etc)
• Component version: 19.0.3
• Issue found on: API 17 (Below Kitkat)

Describe the problem

Firebase remote config fails to fetch config values on API level below 19. Exception thrown is FirebaseRemoteConfigServerException: Bad Request.

Steps to reproduce:

Run the official sample code - https://github.com/firebase/quickstart-android/tree/master/config on any API 17 emulator. Click on ‘Run the java version …’

• What happened Fetch fails and the exception thrown is com.google.firebase.remoteconfig.FirebaseRemoteConfigServerException with message - Bad request.

Complete trace -

    com.google.firebase.remoteconfig.FirebaseRemoteConfigServerException: Fetch failed: The server returned an unexpected error.
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.createExceptionWithGenericMessage(com.google.firebase:firebase-config@@19.0.3:351)
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.fetchFromBackend(com.google.firebase:firebase-config@@19.0.3:304)
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.fetchFromBackendAndCacheResponse(com.google.firebase:firebase-config@@19.0.3:251)
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.fetchIfCacheExpiredAndNotThrottled(com.google.firebase:firebase-config@@19.0.3:191)
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.lambda$fetch$0(com.google.firebase:firebase-config@@19.0.3:160)
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler$$Lambda$1.then(com.google.firebase:firebase-config@@19.0.3)
        at com.google.android.gms.tasks.zzf.run(Unknown Source)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573)
        at java.lang.Thread.run(Thread.java:841)
     Caused by: com.google.firebase.remoteconfig.FirebaseRemoteConfigServerException: Bad Request
        at com.google.firebase.remoteconfig.internal.ConfigFetchHttpClient.fetch(com.google.firebase:firebase-config@@19.0.3:189)
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.fetchFromBackend(com.google.firebase:firebase-config@@19.0.3:278)
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.fetchFromBackendAndCacheResponse(com.google.firebase:firebase-config@@19.0.3:251) 
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.fetchIfCacheExpiredAndNotThrottled(com.google.firebase:firebase-config@@19.0.3:191) 
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler.lambda$fetch$0(com.google.firebase:firebase-config@@19.0.3:160) 
        at com.google.firebase.remoteconfig.internal.ConfigFetchHandler$$Lambda$1.then(com.google.firebase:firebase-config@@19.0.3) 
        at com.google.android.gms.tasks.zzf.run(Unknown Source) 
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1080) 
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:573) 

Upon further inspection, looks like the analyticsUserProperties user property is wrongly formatted in the request body. on API 17 -

{
	"platformVersion": "17",
	"languageCode": "en_GB",
	"analyticsUserProperties": "{}",
	"appId": "[REDACTED]",
	"packageName": "com.google.firebase.quickstart.invites",
	"appVersion": "1.0",
	"appInstanceId": "REDACTED",
	"appInstanceIdToken": "REDACTED",
	"countryCode": "GB",
	"timeZone": "Asia\/Calcutta",
	"sdkVersion": "19.0.3"
}

Response -

{
	"error": {
		"code": 400,
		"message": "Invalid value at 'analytics_user_properties' (type.googleapis.com/google.firebase.remoteconfig.v1.FetchRemoteConfigRequest.AnalyticsUserPropertiesEntry), \"{}\"",
		"status": "INVALID_ARGUMENT",
		"details": [{
			"@type": "type.googleapis.com/google.rpc.BadRequest",
			"fieldViolations": [{
				"field": "analytics_user_properties",
				"description": "Invalid value at 'analytics_user_properties' (type.googleapis.com/google.firebase.remoteconfig.v1.FetchRemoteConfigRequest.AnalyticsUserPropertiesEntry), \"{}\""
			}]
		}]
	}
}

on API 21 -

{
	"platformVersion": "17",
	"languageCode": "en_GB",
	"analyticsUserProperties": {},
	"appId": "[REDACTED]",
	"packageName": "com.google.firebase.quickstart.invites",
	"appVersion": "1.0",
	"appInstanceId": "REDACTED",
	"appInstanceIdToken": "REDACTED",
	"countryCode": "GB",
	"timeZone": "Asia\/Calcutta",
	"sdkVersion": "19.0.3"
}

If JSONObject().toString() is done on a nested map objects it produces "{}" instead of just {}, on API(17). If someone could explain this that would be doubly helpful, thanks.

Between, on remote config version 18.0.0 it works fine.

[clp93]

Hey @Protino, RC SDK Version 19.0.4 should have the fix you’re looking for.

We’ve verified that the regression was not observed on our test devices running API 18 with the new SDK, and as such, I’ll mark the issue as closed.

Thanks for the report!

[Protino]

@clp93 Thanks. Not immediately required as of now, will continue to use 18.0.0. Will close the issue once a fix is available in production.