Atari ST TOS Error -46 — Drive Not Ready

What Does This Error Mean?

TOS error -46 — EDRVNR — means the drive you tried to access isn't ready.
For floppy: no disk, door open, or write-protect tab interfering.
For hard drive: power off, ACSI/SCSI cable loose, or driver not loaded at boot.
Insert a disk or check power and cabling, then try again.

Affected Models

Atari 520ST
Atari 1040ST
Atari Mega ST
Atari STE
Atari Mega STE
Atari TT030
Atari Falcon030

Common Causes

No disk in floppy drive
Floppy drive door not closed
Hard drive powered off or not booted yet
ACSI/SCSI cable disconnected
Hard drive driver (HDX, AHDI, ICD, HDDriver) not in AUTO folder

How to Fix It

For floppy drive issues: insert and close.

Make sure the disk is fully inserted, label-up.
The floppy drive door (on external models) must be closed.
If using a 360KB single-sided disk in a TOS that expects double-sided, try a different disk.
For hard drive: check power.

External hard drives need their own power.
Confirm the drive's power LED is lit.
SH204, Megafile 30, ICD units all have their own switch on the back.
Check the ACSI cable.

The ACSI ribbon cable to the hard drive can work loose.
Power everything off, reseat the cable at both ends, then power on.
Confirm the driver is loaded.

Boot the ST and watch for the driver banner — AHDI, ICD, HDDriver, HDX.
It should appear during the AUTO folder run, before the desktop loads.
If you don't see it, the driver was removed or its file is missing.
Reinstall from your driver disk.
Try a hard reset.

Press the reset button on the ST or power-cycle.
Some hardware glitches clear with a cold boot.
If error -46 persists on the same drive every time, the drive itself may be failing.

Frequently Asked Questions

Can I use modern SD-to-ACSI adapters instead of an old hard drive?

Yes — UltraSatan and ACSI2STM are popular and remove the failure modes of 30-year-old MFM drives.
They mount SD cards as ACSI hard disks.
Pair with HDDriver 11.x for best compatibility.