First of all, make sure you are looking to build a Progressive Web App
Start with a fresh install of version 3.4 and then copy your application's unique files from the old app to the new one. Make sure to read the rest of the upgrade guide before you start the upgrade process.
You also have the option to just upgrade Laravel 5.3 to 5.4 in your previous application by following the steps available on the Laravel docs.
Dingo/api has been removed from the starter, but if you're already relying it, you can simply install it as mentioned in their docs.
Version 3.4 Changelog
It is recommended that you carefully read the changelog for version 3.4.0 so you can get to know most of the new features included in version 3.4
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