React Router BrowserRouter非根路由返回401 Unauthorized错误求助

刚学习React Router，正在将一个使用哈希路由的项目重构为使用BrowserRouter。测试时发现，只有根路由（localhost:3000/）可正常加载对应页面，在localhost:3000/后输入任意内容，无论app.jsx中是否存在对应Route，都会返回401 Unauthorized错误。

推测问题在于：index.html文件未被正确提供给浏览器，存在认证拦截阻止浏览器获取该文件。

已尝试的解决方法 #

• 切换为HashRouter可解决问题，但不清楚原因；
• 检查Network标签，对比之前成功项目的请求，未发现异常，附失败请求信息：

  请求URL: http://localhost:3000/register
  请求方法: GET
  状态码: 401 Unauthorized
  远程地址: 127.0.0.1:3000
  Referrer Policy: strict-origin-when-cross-origin
  Connection: keep-alive
  content-length: 35
  Content-Type: application/json; charset=utf-8
  Date: Mon, 13 Mar 2023 18:16:02 GMT
  ETag: W/"23-NPT3XhyBFeUKvS1KZ/jc0dymZSA"
  Keep-Alive: timeout=5
  X-Powered-By: Express
  Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,/;q=0.8,application/signed-exchange;v=b3;q=0.7
  Accept-Encoding: gzip, deflate, br
  Accept-Language: en-US,en;q=0.9
  Connection: keep-alive
  Cookie: connect.sid=s%3AeT5IKOFT3GsMAeTlpNuEnbP5vy3beQXK.mucLgb13MH5y0YQRLefsHn5AT02no8BVUQukNPwrUa8
  Host: localhost:3000
  If-Modified-Since: Mon, 13 Mar 2023 16:23:19 GMT
  If-None-Match: W/"281-186dbc88f8a"
  sec-ch-ua: "Chromium";v="110", "Not A(Brand";v="24", "Google Chrome";v="110"
  sec-ch-ua-mobile: ?0
  sec-ch-ua-platform: "Linux"
  Sec-Fetch-Dest: document
  Sec-Fetch-Mode: navigate
  Sec-Fetch-Site: none
  Sec-Fetch-User: ?1
  Upgrade-Insecure-Requests: 1
  User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.0.0 Safari/537.36

• 移除app.jsx中除Routes和Route外的所有代码，排除了上下文或旧用户认证的影响。

已排查一周仍未解决，寻求相关帮助。

内容的提问来源于stack exchange，提问作者Cameron Peck