Zend certified PHP/Magento developer

Unable to mount a USB disk on Raspberry Pi 4

I’m trying to mount a USB disk on a Raspberry Pi running Ubuntu 19.10 (arm64 kernel 5.3.0-1007-raspi2) and I’m getting the following errors (it seems to switch between the two):

tom@cl0:/tmp$ sudo mount /dev/sda mnt
mount: /tmp/mnt: mount(2) system call failed: Structure needs cleaning.
tom@cl0:/tmp$ sudo mount /dev/sda mnt
mount: /tmp/mnt: wrong fs type, bad option, bad superblock on /dev/sda, 
missing codepage or helper program, or other error.

blkid returns:

/dev/sda: LABEL="Skynet" UUID="85e8dbfd-7f8f-4bcd-ad69-bf593504854f" TYPE="ext3"

The disk contains a single filesystem (no partitions), which is unusual, but shouldn’t be an issue.

Mounting on another linux host (Debian Testing, kernel 5.2.0-3-amd64)

Does anyone have any idea what’s going on here?