# PKCE - Code Challenge Method not supported **URL:** \ **Category:** API and Webhooks\ **Created:** [June 1, 2021, 9:35am UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510 "2021-06-01T09:35:42Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![AJW](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/ajw/32/27775_2.png) [@AJW](https://devforum.zoom.us/u/AJW)\ **Post date:** [June 1, 2021, 9:35am UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/1 "2021-06-01T09:35:42Z")
**Description** I’m attempting to add PKCE to an OAuth flow that previously worked. Setting `code_challenge_method=S256` looks like it should work, according to the RFC and Zoom’s documentation, so what am I missing here? **Error** Web browser displays an error “Code Challenge Method not supported. (4,715)” **Which App Type (OAuth / Chatbot / JWT / Webhook)?** OAuth **Which Endpoint/s?** `https://zoom.us/oauth/` **How To Reproduce (If applicable)** Steps to reproduce the behavior: 1. Submit a URL like `https://zoom.us/oauth2/login?client_id={_}&response_type=code&redirect_uri={_}&state={_}&code_challenge={_}&code_challenge_method=S256&_x_zm_rtaid={_}&_x_zm_rhtaid={_}` where {\_} represents the redacted parts. 1. Error messages appears “Code Challenge Method not supported. (4,715)” ---
**Author:** ![MaxM](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/maxm/32/42303_2.png) [@MaxM](https://devforum.zoom.us/u/MaxM)\ **Post date:** [June 1, 2021, 10:37pm UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/2 "2021-06-01T22:37:55Z")
Hey @AJW, Thank you for reaching out to the Zoom Developer Forum. I’ve been investigating a similar issue and have added your case to the open issue with our engineering team. I’ll be sure to keep you updated. (ZOOM-276777) Thanks, Max ---
**Author:** ![Jonas](https://avatars.discourse-cdn.com/v4/letter/j/aeb1de/32.png) [@Jonas](https://devforum.zoom.us/u/Jonas)\ **Post date:** [June 3, 2021, 11:57am UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/3 "2021-06-03T11:57:24Z")
Hey @MaxM , Same issue here (4.715). I am implementing Zoom OAuth2 for a Flutter desktop app using the oauth2 package. I actually had to modify the package and remove PKCE in order to get the authentication to work. I appreciate your support, Jonas ---
**Author:** ![MaxM](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/maxm/32/42303_2.png) [@MaxM](https://devforum.zoom.us/u/MaxM)\ **Post date:** [June 4, 2021, 6:04pm UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/4 "2021-06-04T18:04:41Z")
@Jonas @AJW Try using the value `sha256` for the code\_challenge\_method parameter and let us know if that resolves your issues. We’ll update our documentation around this. Thanks, Max ---
**Author:** ![MaxM](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/maxm/32/42303_2.png) [@MaxM](https://devforum.zoom.us/u/MaxM)\ **Post date:** [June 4, 2021, 11:12pm UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/5 "2021-06-04T23:12:19Z")
As an update, you will want to make sure that you are using lowercase letters: `sha256` Max ---
**Author:** ![AJW](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/ajw/32/27775_2.png) [@AJW](https://devforum.zoom.us/u/AJW)\ **Post date:** [June 8, 2021, 8:56am UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/6 "2021-06-08T08:56:04Z")
This resolves the issue, thank you for the updated information. ---
**Author:** ![MaxM](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/maxm/32/42303_2.png) [@MaxM](https://devforum.zoom.us/u/MaxM)\ **Post date:** [June 9, 2021, 12:32am UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/7 "2021-06-09T00:32:23Z")
Hey @AJW, I’m glad that helped! We’ll make sure to update our documentation and will support different cases in the future. Thanks, Max ---
**Author:** ![MaxM](https://sea2.discourse-cdn.com/flex016/user_avatar/devforum.zoom.us/maxm/32/42303_2.png) [@MaxM](https://devforum.zoom.us/u/MaxM)\ **Post date:** [June 9, 2021, 12:32am UTC](https://devforum.zoom.us/t/pkce-code-challenge-method-not-supported/51510/8 "2021-06-09T00:32:28Z")