CORS problem with Cloud 9 IDE

Deliverables: - Correct and secure (no shortcuts!) setup of CORS. - While you're busy, replace a line of code with an environmental variable Our website / user portal is written in Node.js and React.js, using Express and Webpack. Running it locally in Cloud9 IDE (so the old Cloud 9, not the one for Amazon AWS), I get a CORS error, refusing the connection between the front-end and the API. Suspected cause is that the Cloud9 proxy produces a redirect. So I'm looking for someone who knows everything about CORS issues. If you're interested, please quote a fixed price. The error: Access to XMLHtmlRequest /name/22:1 at ‘URL’ from ‘URL’ has been blocked by CORS policy: Response to preflight request doesn’t pass access control check: Redirect is not allowed for a preflight request. The existing CORS setup: [login to view URL]((req, res, next) => { [login to view URL]("Access-Control-Allow-Credentials", "true"); [login to view URL]("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept, Set-Cookie, *"); [login to view URL]("Access-Control-Allow-Origin", "*"); if ([login to view URL]("origin") && [login to view URL]("origin") !== "[Object object]") { [login to view URL]("Access-Control-Allow-Origin", [login to view URL]("origin")); } next(); });