Part 1. Solve Apple Music Error by changing the Phone Settings
After you subscribe to the Apple Music premium membership, you will get access to radio, podcasts as well as download songs, albums for offline listening. The files are in M4P format with AAC codec with DRM protection. Generally they should work perfectly on iOS devices.
If you still encounter error, this is mostly likely related to the network connection or iOS settings. You can try to change the related settings on your iPhone.
Relaunch the Music App
Although Apple has spent much effort on optimizing its Music app on iPhone, there are still some unknown bugs causing some small glitches. Closing the app and launch it again will remove some possible playback errors.
Reset Wifi Network
Apple Music can be downloaded for offline listening. But it also constantly requires network to check and verify that you are a legal subscriber. Else your M4P format music files maybe not recognized without network connection.
Generally you just need to click the "Reset" button from your router or simply power off and power on.
Turn On/Off AirPlane Mode
If you are using the cellular data on your mobile phone, there is not an option to reset it directly. But don't worry, you can apply the same effect by turning on the Airplane mode and switch it off later. You just need to click "Settings" on your iPhone, then you can switch the button On/Off next to the "Airplane Mode".
Force Quit Your Phone
If you don't want to be bothered on changing any settings, another easy way is to restart your mobile. This operating instruction maybe varied on different Android phones. For iPhone, you can long press the power and sleep buttons simultaneously until you see the Apple icon. After that, it should make your Apple Music work well again.
Update iOS System
Whenever there is a bug on the iOS, Apple will usually release a small updated pack within a few days. But we don't recommend you to try it often because it may do some harm to your hardware. If you do want to do that, you need to backup your data first too.