Resolving the PluginRegistrantCallback is not set Error in Flutter for Background Notifications

Описание: Learn how to fix the `PluginRegistrantCallback is not set` error in your Flutter application when handling background notifications with Firebase Cloud Messaging.
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This video is based on the question https://stackoverflow.com/q/66531910/ asked by the user 'Emanuel Developer' ( https://stackoverflow.com/u/14663325/ ) and on the answer https://stackoverflow.com/a/66534102/ provided by the user 'yahya007' ( https://stackoverflow.com/u/14990718/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Troubleshooting the PluginRegistrantCallback is not set Error in Flutter

When developing with Flutter, one common issue developers face is the error: PluginRegistrantCallback is not set. This particular problem typically arises when implementing background notifications using Firebase Cloud Messaging (FCM). In this guide, we'll break down the causes of the issue and provide you with a step-by-step guide to resolve it, ensuring that your app handles notifications properly even when it's closed.

Understanding the Problem

What Causes the Error?

The error PluginRegistrantCallback is not set usually indicates a misconfiguration within your application's .java or .kt file, particularly related to your Flutter plugins. This is critical when the app is in the background or completely closed, as the FCM needs to invoke the right callbacks to deliver notifications.

Steps to Resolve the Error

To fix the PluginRegistrantCallback is not set issue in your Flutter application, follow these steps:

Step 1: Update Your Application Class

You will need to modify your Application.java class (or Application.kt if you are using Kotlin). Here's what you should do:

Create a Custom Plugin Registrant:

This will ensure that the necessary plugins are registered correctly. Below is the code to include in a new file named CustomPluginRegistrant.java (or modify if already exists):

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

Step 2: Modify Your Main Application Class

Next, ensure that your main application class is set up to call this custom registrant. Depending on your app setup, this might look like the following:

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

Step 3: Optional - Remove Unused Plugins

If you are not utilizing the local notifications plugin, feel free to remove that part from the CustomPluginRegistrant.java to streamline your code:

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

Step 4: Test Your App

After implementing these changes, run your app again. Ensure that your notification handlers are set up correctly and check if background notifications are working as expected.

Conclusion

By following these steps, you should have resolved the PluginRegistrantCallback is not set error in your Flutter application. This setup allows your app to receive notifications regardless of its state, thanks to the proper registration of plugins.

If you have further questions or run into more issues, feel free to reach out! Happy coding!