Troubleshooting & FAQ for Android and Firebase

I'm getting an error that the ktx library failed to resolve or could not be found.

This error is likely because you're using the Firebase BoM and specifying a KTX module as your product library dependency.

In July 2025, we stopped releasing new versions of the KTX modules, and we removed the KTX libraries from the Firebase Android BoM (v34.0.0).

If you use KTX APIs from previously released KTX modules, we recommend that you migrate your app to use KTX APIs from the main modules instead. For details, see the FAQ about this initiative.

Do I need to provide a SHA-1 when adding an Android app to a Firebase project?

SHA-1 information is required by Firebase Authentication (when using Google signin or phone number signin) and Firebase Dynamic Links. If you're not using these features, you don't have to provide a SHA-1.

How do I resolve this error: "An OAuth2 client already exists for this package name and SHA-1 in another project"?

This error occurs if we detect that another Firebase or Google Cloud project contains an OAuth 2.0 client ID with the package name and SHA-1 that you specified. Learn how to resolve this error.

When I add Firebase to my Android project, I get a "Could not find" error.

This error usually means that your app is missing one or more references to Google's Maven repository. Make sure to include Google's Maven repository (google()) in your Gradle Configuration file.

• If your project is using the plugins syntax, include it in the plugins section in your settings.gradle.kts or settings.gradle file.
• If your project is using the buildscript syntax, include it in both the buildscript and allprojects sections in your project-level build.gradle.kts or build.gradle file.

Google Sign-in is showing the error "12500:" after I released my app. How do I fix it?

There are two possible reasons why this would happen: you haven’t provided a support email or you’re missing a SHA key. In order to fix this error, make sure all of these conditions are true:

• You've added a support email to the General Settings of your project in the Firebase console.
• You've added the SHA-1 Certificate fingerprint from your release/production keystore to your Firebase Android App in the Firebase console (go to settings Project settings, scroll down to Your apps, and then select your Android App).
• You've added the SHA-1 Certificate fingerprint from the Google Play Console to your Firebase Android App in the Firebase console (go to settings Project settings, scroll down to Your apps, and then select your Android App).

How to add Firebase plugins to an Android project using the buildscript syntax?

Firebase has the following Gradle plugins:

Here's how to add a Firebase plugin to an Android project that still uses the buildscript syntax:

1. In your root-level (project-level) Gradle file (<project>/build.gradle.kts or <project>/build.gradle), add the plugin as a dependency using its Maven coordinates:

   Kotlin

   buildscript{
   repositories{
   // Make sure that you have the following two repositories
   google()// Google's Maven repository
   mavenCentral()// Maven Central repository
   }
   dependencies{
   ...
   // Add the Maven coordinates and latest version of the plugin
   classpath("PLUGIN_MAVEN_COORDINATES:PLUGIN_VERSION")
   }
   }
   allprojects{
   ...
   repositories{
   // Make sure that you have the following two repositories
   google()// Google's Maven repository
   mavenCentral()// Maven Central repository
   }
   }
   

   Groovy

   buildscript{
   repositories{
   // Make sure that you have the following two repositories
   google()// Google's Maven repository
   mavenCentral()// Maven Central repository
   }
   dependencies{
   ...
   // Add the Maven coordinates and latest version of the plugin
   classpath'PLUGIN_MAVEN_COORDINATES:PLUGIN_VERSION'
   }
   }
   allprojects{
   ...
   repositories{
   // Make sure that you have the following two repositories
   google()// Google's Maven repository
   mavenCentral()// Maven Central repository
   }
   }
   

2. In your module (app-level) Gradle file (usually <project>/<app-module>/build.gradle.kts or <project>/<app-module>/build.gradle), add the plugin using its plugin ID:

   Kotlin

   plugins{
   id("com.android.application")
   // Add the ID of the plugin
   id("FIREBASE_PLUGIN_ID")
   ...
   }
   

   Groovy

   plugins{
   id'com.android.application'
   // Add the ID of the plugin
   id'FIREBASE_PLUGIN_ID'
   ...
   }