Windows on a Mac: "Incorrect function" error

Started by Yukio

Yukio

Windows on a Mac: "Incorrect function" error   18 March 2019, 17:37

We were testing RAMDisk Software on Windows 10 that is run on 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 a Windows error messages "Unable to access RAM Disk", "That place is not used" and "Incorrect function". It is very strange because RAM Disk volume is created in displayed in RAM Disk software.

Do you know anything about phenomenon, why this is happening? Could you let us know if possible.
SoftPerfect Support forum - Ann avatar image
Ann

Re: Windows on a Mac: "Incorrect function" error   18 March 2019, 18:09

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.

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