Error Code Portal
MicrosoftWindows Win32Error code

1281

ERROR_ALREADY_THREAD

Alternative forms: 0x00000501 · 0x501 · ERROR_ALREADY_THREAD · 0x80070501

What does this code mean?

Code 1281 · An issue reported by Windows Win32.

Official explanation · Original text

The current thread has already been converted from a fiber.

Troubleshooting and diagnostic links

First check that the document's product, version, and environment match your situation.

Source and terms of use

System Error Codes (1000-1299) (WinError.h) ↗

Creator: Microsoft and MicrosoftDocs contributors
License: Creative Commons Attribution 4.0 International
Checked on: 2026-11-12

Modifications: Extracted numeric codes, symbolic names and English message text; converted Markdown/HTML to plain text and normalized whitespace; added Korean product context, namespace labels, status classification and separately labeled official links. No machine translation of message text.

Source details · Original licenses and notices