相关文章推荐
追风的机器猫  ·  在 ASP.NET Core ...·  1 周前    · 
开心的棒棒糖  ·  element ui Error in ...·  7 月前    · 
爱看球的机器猫  ·  Spring Boot ...·  9 月前    · 
俊逸的火锅  ·  flutter ...·  1 年前    · 

Join Private Q&A

Setup a private space for you and your coworkers to ask questions and share information. Learn more about Teams

I have followed this step to setup my server to enable CORS. https://docs.microsoft.com/en-us/aspnet/web-api/overview/security/enabling-cross-origin-requests-in-web-api

But now in my browser dev console, I see this error message:

XMLHttpRequest cannot load https://serveraddress/abc . Response for preflight is invalid (redirect)

Do you know what can I do to fix it? I am making a CORS request in HTTPS. I think that is causing the 'preflight is invalid (redirect)' failure. But I don't know why or what is redirecting the OPTIONS request.

Thank you.

Your code is triggering your browser to send a CORS preflight OPTIONS request , and the server’s responding with a 3xx redirect. It needs to respond with a 2xx success message instead.

You may be able to adjust your code to avoid triggering the browser to send the OPTIONS request.

As far as what all’s going on in this case, it’s important to know that browsers do a CORS preflight if:

  • the request method is anything other than GET , HEAD , or POST
  • you’ve set custom request headers other than Accept , Accept-Language , Content-Language , Content-Type , DPR , Downlink , Save-Data , Viewport-Width , or Width
  • the Content-Type request header has a value other than application/x-www-form-urlencoded , multipart/form-data , or text/plain
  • If you can’t change your code to avoid need for browsers to do a preflight, then another option is:

  • Examine the URL in the Location response header in the response to the OPTIONS request.
  • Change your code to make the request to that other URL directly instead.
  • The difference between the URLs might be something as simple as a trailing slash in the path — for example, you may need to change the URL in your code to http://localhost/api/auth/login/ (notice the trailing slash) rather than http://localhost/api/auth/login (no trailing slash).

    You can use the Network pane in browser devtools to examine the response to the OPTIONS request and to find the redirect URL in the value of the Location response header.

    Thanks for your answer. i will follow your advice. My app need to send Content-Type application/json to server so that is what triggers the pre-flight. And I can't change that. n179911 Feb 12 '17 at 7:04

    Thanks for contributing an answer to Stack Overflow!

    • Please be sure to answer the question . Provide details and share your research!

    But avoid

    • Asking for help, clarification, or responding to other answers.
    • Making statements based on opinion; back them up with references or personal experience.

    To learn more, see our tips on writing great answers .

    site design / logo © 2019 Stack Exchange Inc; user contributions licensed under cc by-sa 3.0 with attribution required . rev 2019.7.22.34392