Error Code Portal
MicrosoftWindows WinHTTPError code

12100

ERROR_WINHTTP_CANNOT_CALL_BEFORE_OPEN

Alternative forms: 0x00002F44 · 0x2F44 · ERROR_WINHTTP_CANNOT_CALL_BEFORE_OPEN

What does this code mean?

Code 12100 · An issue reported by Windows WinHTTP.

Official explanation · Original text

Returned by the HttpRequest object if a requested operation cannot be performed before calling the Open method.

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