: For those who want the original interface, community-patched versions like YouTube Vanced (v16.29.39) sometimes still work if you install the corresponding MicroG to manage your Google login.
: To fix server errors (like Error 400), you may need to go to ReVanced Settings > Miscellaneous > Spoof app version and target a modern version like 4. Legacy APK Versions (Limited Use)
If you hate ads, want background play, and don't care about Google login, is superior to the official YouTube app. app youtube android 5.1.1
The official app relies on Google Play Services and internal YouTube APIs to fetch video feeds, comments, and user data. When Google deprecates older versions of these APIs, the software installed on your Android 5.1.1 device can no longer communicate with YouTube’s servers, resulting in a permanent offline error. Hardware and Security Bottlenecks
Background playback, video downloading, and zero advertisements. : For those who want the original interface,
To retain usability on Android 5.1.1, avoid the official app and use third‑party clients:
Official support for Android 5.1.1 has effectively ended. While you may still have the app on your device, you are likely encountering "Update Required" prompts or "Server 400" errors. The official app relies on Google Play Services
: Unlock the bootloader and install a custom recovery like TWRP.