react production build 404 not found

This is a common issue that comes up for SPA. In SPA, mostly the routing happens on client side. In your case, mostly react-router should be doing the job. Since the whole js is bundled as a single file and is served in index.html, you need to serve index.html for all paths that is non-existing in your server.

You have to add a config like this

RewriteEngine On  RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -f [OR]RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -dRewriteRule ^ - [L]RewriteRule ^ /index.html [L]

So, if there is no matching path in your server, the index.html would get served. Then the javascript would execute and react-router(client side routing) will take over and display the correct component for the route.

This is true for most SPA, where the routing happens on client side.

Using web.config for IIS Window 10

    <?xml version="1.0" encoding="utf-8"?><!--  For more information on how to configure your ASP.NET application, please visit  https://go.microsoft.com/fwlink/?LinkId=169433  --><configuration>  <system.webServer>    <rewrite>  <rules>    <rule name="Imported Rule 1" stopProcessing="true">      <match url="^" ignoreCase="false" />      <conditions logicalGrouping="MatchAny">        <add input="{DOCUMENT_ROOT}{URL}" matchType="IsFile" ignoreCase="false" />        <add input="{DOCUMENT_ROOT}{URL}" matchType="IsDirectory" ignoreCase="false" />      </conditions>      <action type="None" />    </rule>    <rule name="Imported Rule 2" stopProcessing="true">      <match url="^" ignoreCase="false" />      <action type="Rewrite" url="/index.html" />    </rule>  </rules></rewrite>  </system.webServer>  <system.web>    <customErrors mode="Off" />    <httpRuntime targetFramework="4.6.1" executionTimeout="240" maxRequestLength="2048000" />    <trace enabled="true" requestLimit="40" localOnly="false" />  </system.web>  <system.webServer>    <defaultDocument>      <files>        <clear />        <add value="Index.aspx" />        <add value="Default.htm" />        <add value="Default.asp" />        <add value="index.htm" />        <add value="index.html" />        <add value="iisstart.htm" />        <add value="default.aspx" />      </files>    </defaultDocument>    <directoryBrowse enabled="false" />  </system.webServer></configuration>