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

This error is likely because you're using theFirebase 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 theFirebase Android BoM (v34.0.0).

If you use KTX APIs from previously released KTX modules, we recommend that youmigrate your app to use KTX APIs from the main modules instead. For details, see theFAQ 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 byFirebase Authentication (when usingGoogle signin orphone number signin) andFirebase 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 orGoogle Cloud project contains an OAuth 2.0 client ID with the package name and SHA-1 that you specified. Learn how toresolve 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 theplugins syntax, include it in theplugins section in yoursettings.gradle.kts orsettings.gradle file.
• If your project is using thebuildscript syntax, include it in both thebuildscript andallprojects sections in your project-levelbuild.gradle.kts orbuild.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 sureall of these conditions are true:

• You've added a support email to theGeneral Settings of your project in theFirebase console.
• You've added theSHA-1 Certificate fingerprint from your release/production keystore to your Firebase Android App in theFirebase console (go tosettingsProject settings, scroll down toYour apps, and then select your Android App).
• You've added theSHA-1 Certificate fingerprint from theGoogle Play Console to your Firebase Android App in theFirebase console (go tosettingsProject settings, scroll down toYour apps, and then select your Android App).

How to add Firebase plugins to an Android project using thebuildscript syntax?

Firebase has the following Gradle plugins:

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

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

   Kotlin

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

   Groovy

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

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

   Kotlin

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

   Groovy

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

What open source notices should I include in my app?

The Firebase Android SDK contains ahelperActivity for showing license information.