# Error: redefinition of module 'CFURLSessionInterface' (Compiling my first hello.swift on Windows 10)

**URL:** <https://forums.swift.org/t/error-redefinition-of-module-cfurlsessioninterface-compiling-my-first-hello-swift-on-windows-10/47166>\
**Category:** Using Swift\
**Tags:** windows\
**Created:** [April 5, 2021, 5:31pm UTC](https://forums.swift.org/t/error-redefinition-of-module-cfurlsessioninterface-compiling-my-first-hello-swift-on-windows-10/47166 "2021-04-05T17:31:47Z")\
**Posts on this page:** 1\
**Showing post:** 2

<div class="post-metadata">

**Author:** ![zcyemi](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/zcyemi/32/16507_2.png) [@zcyemi](https://forums.swift.org/u/zcyemi)\
**Post date:** [April 13, 2021, 12:54am UTC](https://forums.swift.org/t/error-redefinition-of-module-cfurlsessioninterface-compiling-my-first-hello-swift-on-windows-10/47166/2 "2021-04-13T00:54:07Z")

</div>

use `set SWIFTFLAGS=-sdk %SDKROOT%`

mentioned from [this](https://forums.swift.org/t/found-some-solutions-when-troubleshooting-installing-swift-on-windows/44467)

---

_[View the full topic](https://forums.swift.org/t/error-redefinition-of-module-cfurlsessioninterface-compiling-my-first-hello-swift-on-windows-10/47166)._