How do I resolve this unknow error (100030)?

I encountered the same issue. I was unable to transfer pictures from a hard drive connected to my Mac to my iPhone. I resolved this by moving the pictures to my Mac first, which allowed the transfer to proceed successfully.

I hope that it will work for somebody else here.

Nice day

Hi there Bole_Road103,

Can you tell us the device you are using Apple Music on? That can help us determine what might be going on and possible next steps.

One step you can take to see if that may help resolve this unknown error is to either quit the Apple Music app or, if relevant, sign out of the web browser for Apple Music then sign back in and try again. If needed, the articles below may help depending on the device you're using:

• Close an app on your iPhone or iPod touch
• Quit apps on Mac

Please let us know if that helps or if you've already tried those steps.

Take care.