You've made a request to EAS Update without the required request headers.
If you are manually fetching the manifest from the Expo servers with a command like wget or curl, you can specify the missing information in query parameters instead of request headers for an easier debugging experience. See more details here.
If you've encountered this error after running npx expo prebuild and have built locally instead of using EAS Build, make sure you've followed the correct steps to configure EAS Update. See here and here for more information.
If your app is encountering this error and you've already completed the setup guide, verify that you've configured EAS Update correctly by following this guide.