Windows Error Code Lookup

Searches Win32 system error codes, NTSTATUS values, and common HRESULT constants at once — enter a hex value (with or without 0x), a decimal value (including the negative signed form Windows sometimes logs), or a symbolic name like ERROR_ACCESS_DENIED or STATUS_ACCESS_VIOLATION. A hex value with the high bit set is also decoded as an HRESULT (severity/facility/code) — most HRESULTs seen in practice wrap a plain Win32 error (FACILITY_WIN32), which is resolved back to that underlying error automatically. Extends this site's existing NTSTATUS Lookup to cover the other two Windows error code spaces rather than duplicating it. Runs entirely client-side; nothing you type is sent anywhere.

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Where this data comes from

NTSTATUS values are this site's existing 1,799-entry dataset, sourced from Microsoft's [MS-ERREF] specification. Win32 error codes (164 of the most common ones, not the full ~800+ in WinError.h) are pulled directly from Microsoft's own System Error Codes documentation pages, not retyped from memory. "Typical causes" and "common fixes" are only shown for a curated subset of around 40 operationally significant codes — the rest show Microsoft's own description text only, rather than inventing investigation notes for codes nobody's actually verified. HRESULT coverage is a modest curated list of common standalone constants (COM/Automation/SSPI/certificate errors) plus the bit-math decode that handles every Win32-wrapped HRESULT automatically — it is not an exhaustive HRESULT reference.