Hi all, I am using Rest Api to get/avail the access token, but getting this error when using client_id and client_secret to generate access_token.
Hi @Ux_User 
Having looked into that error internally, it is a bot-protection challenge that can appear when a request looks automated or originates from a flagged IP/network. It’s not an error from Shopify’s OAuth API itself.
Before digging into the that side though, it would help to understand what you’re building. If you own the store and just need API access for your own integration, you don’t need the browser-based OAuth flow at all. The client credentials grant lets you POST directly to the token endpoint with your client_id, client_secret, and grant_type=client_credentials, and you get back an access token. No browser redirects, no Cloudflare challenge. The Dev Dashboard access tokens tutorial walks through the full flow with a Node.js example.
If you’re building an app for other merchants and using the authorization code grant, the challenge can appear during the browser redirect to /admin/oauth/authorize.
Could you share which endpoint you’re hitting, the full HTTP request and response (minus credentials), and whether this is happening in a browser or from a server-side call? Also, are you using a VPN, proxy, or running this from a cloud environment like AWS?
Thanks it works!! following the client credential grant.