Nucleus will not recognize USB external hard drive

Roon Core Machine

Nucleus 2.0

Networking Gear & Setup Details

Connected Audio Devices

Number of Tracks in Library

Description of Issue


One of my two external usb hard drives are not recognized by Nucleus and I cannot play most of my music without receiving the following error message:

“Unexpected error communicating with audio device”

Is the external USB drive formatted as NTFS?

Thanks for reaching out. I have been using this ext. hard drive for 3 years and have never had an issue. It is connected via USB to the Nucleus. Apologies for my lack of technical knowledge, below is from the product description:

  • Comes formatted for Windows 10, 8.1, and 7.1. Compatible with Mac and other operating systems after reformatting

Formatted for Windows means NTFS, Microsoft’s file system for Windows, if you didn’t reformat it with a different file system. Your issue sounds like it might be caused by the better/safer but therefore stricter NTFS support that was added in RoonOS build 254 in November. There were quite many of these issues because it was discovered that quite many people had been using NTFS external disks that were not in the best state, which had previously gone unnoticed.

The disk may have been previously unsafely removed (unplugged either from a PC without going through the safe remove procedure or unplugged from a running Nucleus), which would leave an “unsafely removed” flag on the file system. Current RoonOS versions have become picky about this for safety reasons (unsafely removed NTFS file systems are prone to later corruption) and it may refuse to access it until this is fixed. (It’s also possible that a random error occurred on its own)

It’s possible / probably necessary to clean it up with a Windows PC by attaching it, opening a command prompt as Administrator, and running the CHKDSK /f command for the disk. Find detailed instructions in this post:

(Note that the other posts in this topic are unrelated to your issue, but this post describes the check procedure you should perform and also provides a bit of background)

After this, remove it safely from Windows as described here:

In the future, also ensure that you shut down the Nucleus before removing the disk. (The same thing could also happen due to a power cut though)

Also note that the Roon OS documentation advises against using NTFS if possible. Apart from the unclean removal issue, it’s a proprietary and by Microsoft poorly documented file system that is difficult to support 100% in open operating systems like Linux (that Roon OS is based on), although the new driver is very good - but picky about working only with error-free disks to avoid fatal issues.

Should you decide to reformat the disk, be aware that this will delete all data, so you have to make a backup.


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