Relevant for
The printer is showing the message "USB drive or file error, the print is now paused. Reconnect the drive".
Error name: USB flash disk error
Error code: #31821 (CORE One) #35821 (CORE One L) #26821 (MK4S) #13821 (MK4) #27821 (MK3.9S) #21821 (MK3.9) #28821 (MK3.5S) #23821 (MK3.5) #17821 (XL) #12821 (MINI)
It is possible that the USB drive can come loose. Ensure the USB drive is connected and that the insertion into the connector is not loose.
An issue on the USB drive, such as a corrupt file, can cause the error. Format the USB drive with the procedure from the dedicated article.
Please note that formatting the USB drive means that its files are deleted, including the print in progress, which cannot be resumed.