Windows on a Mac: "Incorrect function" error
2 posts · Closed
We were testing RAM Disk software on Windows 10 that is run on a MacBook Air with Boot Camp.
We installed and set up RAM Disk with no problems. But we can't use/access actual RAM Disk volumes. When we try to access RAM Disk volumes, we saw Windows error messages "Unable to access RAM Disk", "That place is not used" and "Incorrect function". It is very strange because the RAM Disk volume is created and displayed in the RAM Disk software.
Do you know anything about this phenomenon, why this is happening? Could you let us know if possible.
Thank you for the feedback. We have tested this on an iMac running Windows and it indeed was the case. Any attempt to use the disk from Windows Explorer lead to the "Incorrect function" error.
This is likely to be caused by a driver that Apple installs on Windows. This driver doesn't seem to like the presence of a standalone volume, i.e. a disk without partitions. We found the same issue was present in other application that create similar standalone volumes, such as TrueCrypt and VeraCrypt.
The problem can be fixed by either:
- Removing or disabling AppleHFS.sys. This will also make it impossible to open HFS+ volumes from Windows; or
- Enabling Hard Disk Emulation. A complete hard drive will be emulated in this case, with the downside that it may be a little slower.