How to Convert Hex Windows Error Codes to the Meaningful Error Message – 0x80040002 and 0x80040005 and others? – Interview Question of the Week #182

Question: How do we turn a hexadecimal Windows error, such as 0x80070070, into a meaningful message?

Answer: Identify the error family first. For an HRESULT built from a Win32 error, the low 16 bits contain the Win32 error number. You can convert that part to decimal and look up its message. That shortcut is not valid for every HRESULT.

I started looking at this after encountering hexadecimal errors in a SQL Server ERRORLOG. The digits were easy to copy; knowing what they meant took a little more work. Take 0x80070070: the facility is Win32, the low part is hexadecimal 0070, and hexadecimal 70 is decimal 112.

In Command Prompt, look up that decimal code:

NET HELPMSG 112

The result identifies insufficient disk space. The calculator and Command Prompt captures show the same conversion, so they remain useful together.

Check the facility before decoding the low part

You can do both steps in Windows PowerShell:

$hex = '80070070' # HRESULT without the 0x prefix
$value = [uint32]::Parse($hex, [Globalization.NumberStyles]::HexNumber)
$facility = ($value -shr 16) -band 0x1fff
if ($facility -ne 7) {
    throw 'This is not a FACILITY_WIN32 HRESULT. Look up the complete code.'
}
$win32Code = [int]($value -band 0xffff)
[pscustomobject]@{
    HResult = '0x' + $hex
    Win32Code = $win32Code
    Message = ([ComponentModel.Win32Exception]::new($win32Code)).Message
}

The facility check is the important part. For 0x80070070, it is 7, which represents FACILITY_WIN32. The script returns Win32 code 112 and its local Windows message. With 80040005, it refuses that shortcut: this is an OLE/interface error, and interpreting the last digits as Win32 error 5 would incorrectly suggest access denied.

The earlier table incorrectly assigned file, path and access errors to the 0x800400xx OLE codes, including a duplicate entry for 0x80040005. Keep the complete value and the surrounding ERRORLOG message when troubleshooting. The same last few digits in another facility can describe a different problem.

Published by Pinal Dave on SQLAuthority. More of my work at pinaldave.com.