Outdated Firebase Auth library

Oct 13, 2025 by wbrum.org 57 views

Introduction

When building a Flutter Android project, encountering version mismatch errors can be frustrating and time-consuming to resolve. In this article, we will discuss a specific issue where the Firebase Auth library is compiled with Kotlin 2.1.0, but the project is expecting Kotlin 1.9.0. We will explore the possible causes, solutions, and best practices to avoid such issues in the future.

Understanding the Issue

The error message typically indicates that the Firebase Auth library is compiled with a higher version of Kotlin than the project's expected version. This can occur due to various reasons, including:

Incompatible dependencies: When using Firebase Auth, it may be compiled with a specific version of Kotlin that is not compatible with the project's expected version.
Gradle configuration: Incorrect or outdated Gradle configuration can lead to version mismatch errors.
Kotlin version updates: If the project's Kotlin version is not updated to match the Firebase Auth library's version, it can cause compilation issues.

Possible Causes

Incompatible Dependencies

When using Firebase Auth, it may be compiled with a specific version of Kotlin that is not compatible with the project's expected version. This can occur due to the following reasons:

Outdated Firebase Auth library: If the Firebase Auth library is not updated to the latest version, it may be compiled with an older version of Kotlin.
Incompatible Kotlin versions: If the project's Kotlin version is not compatible with the Firebase Auth library's version, it can cause compilation issues.

Gradle Configuration

Incorrect or outdated Gradle configuration can lead to version mismatch errors. This can occur due to the following reasons:

Outdated Gradle version: If the Gradle version is not updated to the latest version, it may not support the latest Kotlin versions.
Incorrect Kotlin version specification: If the Kotlin version is not specified correctly in the Gradle configuration, it can cause version mismatch errors.

Kotlin Version Updates

If the project's Kotlin version is not updated to match the Firebase Auth library's version, it can cause compilation issues. This can occur due to the following reasons:

Outdated Kotlin version: If the project's Kotlin version is not updated to the latest version, it may not support the latest Firebase Auth library versions.
Incompatible Kotlin versions: If the project's Kotlin version is not compatible with the Firebase Auth library's version, it can cause compilation issues.

Solutions

Update Firebase Auth Library

To resolve the issue, update the Firebase Auth library to the latest version that matches the project's expected Kotlin version. This can be done by adding the following code to the build.gradle file:

dependencies {
    implementation 'com.google.firebase:firebase-auth:21.0.1'
}

Update Gradle Configuration

Update the Gradle configuration to the latest version that supports the latest Kotlin versions. This can be done by adding the following code to the build.gradle file:

buildscript {
    repositories {
        google()
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:7.3.1'
        classpath 'com.google.gms:google-services:4.3.10'
    }
}

Update Kotlin Version

Update the project's Kotlin version to match the Firebase Auth library's version. This can be done by adding the following code to the build.gradle file:

kotlin {
    explicitStandardJvmTarget '11'
}

Best Practices

To avoid version mismatch errors in the future, follow these best practices:

Regularly update dependencies: Regularly update dependencies to the latest versions to ensure compatibility with the project's expected Kotlin version.
Use the latest Gradle version: Use the latest Gradle version to ensure support for the latest Kotlin versions.
Specify Kotlin version correctly: Specify the Kotlin version correctly in the Gradle configuration to avoid version mismatch errors.
Test thoroughly: Test the project thoroughly after updating dependencies or Gradle configuration to ensure that there are no compilation issues.

Conclusion

Introduction

In our previous article, we discussed the issue of Kotlin version mismatch between the Firebase Auth library and the project's expected Kotlin version. We explored the possible causes, solutions, and best practices to avoid such issues in the future. In this article, we will provide a Q&A section to address common questions and concerns related to this issue.

Q&A

Q: What is the cause of the Kotlin version mismatch error?

A: The Kotlin version mismatch error can occur due to various reasons, including incompatible dependencies, incorrect or outdated Gradle configuration, and Kotlin version updates.

Q: How can I resolve the Kotlin version mismatch error?

A: To resolve the Kotlin version mismatch error, update the Firebase Auth library to the latest version that matches the project's expected Kotlin version, update the Gradle configuration to the latest version that supports the latest Kotlin versions, and update the project's Kotlin version to match the Firebase Auth library's version.

Q: What are the possible causes of the Kotlin version mismatch error?

A: The possible causes of the Kotlin version mismatch error include:

Incompatible dependencies: When using Firebase Auth, it may be compiled with a specific version of Kotlin that is not compatible with the project's expected version.
Gradle configuration: Incorrect or outdated Gradle configuration can lead to version mismatch errors.
Kotlin version updates: If the project's Kotlin version is not updated to match the Firebase Auth library's version, it can cause compilation issues.

Q: How can I prevent the Kotlin version mismatch error in the future?

A: To prevent the Kotlin version mismatch error in the future, follow these best practices:

Regularly update dependencies: Regularly update dependencies to the latest versions to ensure compatibility with the project's expected Kotlin version.
Use the latest Gradle version: Use the latest Gradle version to ensure support for the latest Kotlin versions.
Specify Kotlin version correctly: Specify the Kotlin version correctly in the Gradle configuration to avoid version mismatch errors.
Test thoroughly: Test the project thoroughly after updating dependencies or Gradle configuration to ensure that there are no compilation issues.

Q: What are the benefits of using the latest Kotlin version?

A: The benefits of using the latest Kotlin version include:

Improved performance: The latest Kotlin version provides improved performance and better support for modern programming paradigms.
Enhanced security: The latest Kotlin version provides enhanced security features and better support for secure coding practices.
Better support for modern programming paradigms: The latest Kotlin version provides better support for modern programming paradigms, such as functional programming and coroutines.

Q: How can I update the Kotlin version in my project?

A: To update the Kotlin version in your project, follow these steps:

Update the Gradle configuration: Update the Gradle configuration to the latest version that supports the latest Kotlin versions.
Specify the Kotlin version correctly: Specify the Kotlin version correctly in the Gradle configuration to avoid version mismatch errors.
Update the project's Kotlin version: Update the project's Kotlin version to match the Firebase Auth library's version.

Conclusion

In conclusion, the Kotlin version mismatch error between the Firebase Auth library and the project's expected Kotlin version can be frustrating and time-consuming to resolve. By understanding the possible causes, solutions, and best practices, developers can avoid such issues in the future. Regularly updating dependencies, using the latest Gradle version, specifying Kotlin version correctly, and testing thoroughly can help ensure that the project compiles successfully without any version mismatch errors.