Error Code Portal
MicrosoftWindows WinHTTPError code

12155

ERROR_WINHTTP_HEADER_ALREADY_EXISTS

Alternative forms: 0x00002F7B · 0x2F7B · ERROR_WINHTTP_HEADER_ALREADY_EXISTS

What does this code mean?

Code 12155 · An issue reported by Windows WinHTTP.

Official explanation · Original text

Obsolete; no longer used.

Troubleshooting and diagnostic links

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

Source and terms of use

Error Messages (Winhttp.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