Скачать или смотреть Deploying Your Kotlin Spring Boot App to Heroku: Solving the H10 Crashing Issues

When deploying a Kotlin Spring Boot application to Heroku, you might encounter the frustrating `H10` error. Learn how to troubleshoot this issue with essential steps.
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Deploying Your Kotlin Spring Boot App to Heroku: Solving the H10 Crashing Issues

Deploying a Kotlin Spring Boot application to Heroku can be a straightforward process, but sometimes you might run into issues that lead to the dreaded H10 error. If you're facing this issue, where your application crashes immediately upon deployment, you're not alone. Many developers encounter this problem, especially when transitioning from local development to a cloud environment like Heroku. In this guide, we'll dive into the specifics of the H10 error and how to resolve it effectively.

Understanding the H10 Error

When you encounter an H10 error in Heroku, it signals that your application has crashed. The Heroku logs will often show messages that look like the following:

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Essentially, this means that your application tried to start but failed to do so for some reason. One common culprit is incompatibility between the Java runtime version you used for development and the version Heroku uses by default.

Common Causes of the H10 Error

The most frequent cause of the H10 error is an Unsupported Class Version Error. You might see logs like these:

[[See Video to Reveal this Text or Code Snippet]]

This specific message indicates that your Kotlin application has been compiled with a newer version of Java than what Heroku supports by default. By default, Heroku runs Java 8, but if you compiled your application using Java 11, that discrepancy will trigger a crash.

Fixing the H10 Error: Steps to Resolution

To resolve this issue, follow these steps:

1. Specify the Java Runtime Version

The first action to take is to inform Heroku about the Java version your application requires. Create a file named system.properties in the root directory of your application. This file tells Heroku to use the specified Java version during runtime.

Create the file: system.properties

Add the following line:

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2. Rebuild and Redeploy Your Application

After creating the system.properties file, you need to rebuild your application and redeploy it to Heroku:

Commit your changes in Git:

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Push the changes to Heroku:

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3. Verify Your Application Status

Once the deployment is complete, check the status of your application to ensure it's running correctly. You can view the logs to confirm that there are no more H10 errors:

[[See Video to Reveal this Text or Code Snippet]]

Additional Notes

Favicon Requests: If you're seeing requests for /favicon.ico, don't worry! This is common as browsers automatically try to load the favicon. It’s not causing your application to crash, so you can ignore it.

Java Version: Always ensure that your code is compatible with the Java version defined in system.properties to prevent issues during deployment.

Conclusion

Deploying a Kotlin Spring Boot application to Heroku can be smooth as long as you pay attention to environment configurations, particularly the Java runtime version. By following the steps outlined in this post, you should be able to resolve the H10 error and successfully run your application on Heroku. If you continue to face challenges, don't hesitate to dig deeper into your application logs or reach out to the Heroku community for support.

Happy coding!