Fixing ERROR_INVALID_CATEGORY (0x00000073): IOCTL and Control Code Mismatches in Windows

🔸 Introduction

You’re calling DeviceIoControl to talk to a custom device driver, and suddenly ERROR_INVALID_CATEGORY (0x73) is returned. What went wrong? Most likely, you’re using a control code that the driver doesn’t recognize.

🔸 Technical Breakdown

  • Symbolic Constant: ERROR_INVALID_CATEGORY
  • Decimal: 115
  • Hexadecimal: 0x00000073
  • Meaning:
    The control category or function you’re trying to access does not exist for the target device or driver.

🔸 Causes and Context

🔹 Low-Level

  • CTL_CODE improperly defined.
  • User-mode app and driver header files out of sync.
  • IOCTL being issued to a non-supporting device class.

🔹 High-Level

  • Obsolete or improperly installed drivers.
  • Incomplete implementation of driver functionality.

🔸 Solutions

✅ Use Matching Header Files

Ensure both user-mode and kernel-mode code include the same IOCTL definitions.

✅ Define CTL_CODE Properly

c

#define IOCTL_MY_COMMAND CTL_CODE(FILE_DEVICE_UNKNOWN, 0x801, METHOD_BUFFERED, FILE_ANY_ACCESS)

✅ Check Driver Documentation

Verify the supported control codes and categories in the driver’s INF or technical documentation.

✅ Update the Driver

Old drivers may not support newer control codes.

🔸 References

🔸 Metadata

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