To fix the “background execution not allowed” error in Android, you can try the following steps:

1. Make sure that you are not trying to start a background service from the main thread of your app. Android does not allow background execution from the main thread to avoid ANR (Application Not Responding) errors.
2. Check if you have added the necessary permissions in your app’s AndroidManifest.xml file. For example, if you are trying to start a background service, you need to add the android.permission.FOREGROUND_SERVICE permission in your manifest file.
3. Make sure that you are not using any deprecated methods or APIs that are no longer supported in the latest version of Android.
4. If you are using third-party libraries or SDKs, make sure that they are compatible with the latest version of Android and are not causing any conflicts.
5. Try cleaning and rebuilding your project to see if that fixes the issue.
6. If none of the above steps help, you may need to debug your app to find the root cause of the issue. You can use logcat and other debugging tools to identify the problem and fix it.

I hope these suggestions help fix the “background execution not allowed” error in your Android app.