Failed to load <service url>: Request header field X-ijt are not allowed by Access-control-allow-headers in preflight Response.

Use Pycharm,tornado write the background, still use Pycharm write the front-end code, run after the following error:

Failed to load <service url>: Request header field x-ijt is not allowed by Access-Control-Allow-Headers in preflight response.

Cross-domain issues

Solve

Add a pycharm Chrome extension

Right-click the extension and Tap options in the menu:

After filling out, apply.

Again, the error disappears.

Reference: CORS Control in JetBrains Chrome Extension

Failed to load <service url>: Request header field X-ijt are not allowed by Access-control-allow-headers in preflight Response.