Starting from November 19, 2018, when a function is triggered by an HTTP trigger, the server forcibly adds the content-disposition: attachment field in response header. As a result, the return results are open as attachments in the browser.

To remove the preceding restrictions, you can configure a custom domain name to access functions instead of the default domain name aliyuncs.com of Function Compute.

If you cannot resolve the issue by configuring a custom domain name, you can add a response header content-type: text/html.