UseWebpackMiddleware() causes slow initial app startup and, if commented out, causes "__webpack_hmr" resource to constantly be requested from client #363

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fergalmoran · 2025-08-09T17:16:00Z

fergalmoran commented

2025-08-09 17:16:00 +00:00

Originally created by @bfischer on 10/13/2017

I have a React/Redux app that is using the asp.net Core 2.0 template. I've since moved most of the boilerplate code out in exchange for my own stuff, but am using a mostly similar webpack config and package.json (added a few new packages, nothing major). I'm having an issue where, in my Startup.cs, if I comment out the the lines registering the webpack middleware and configuring HMR, my client will constantly ping this __webpack_hmr resource and error out in the console. The app will still run fine, but the console will constantly have these errors written to it. If I leave the HMR configuration present in Startup.cs, I don't get any errors, but the start up time of the app takes much longer. Both of these issues have me concerned for when this hits productions.

Here are the lines I comment out in Startup.cs:

          `  app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions
            {

                HotModuleReplacement = false,
                ReactHotModuleReplacement = false,
                HotModuleReplacementClientOptions = new Dictionary<string, string>
                {
                    { "quiet", "true" }
                }
            }); `

Here is the log in the console when __webpack_hmr is requested
EventSource's response has a MIME type ("text/html") that is not "text/event-stream". Aborting the connection.

That resource is requested once every ~10 seconds. Another issue is that if I enable HMR (uncommenting those lines from above) webpack will constantly keep rebuilding, instead of only when there is a change to a file.

*Originally created by @bfischer on 10/13/2017* I have a React/Redux app that is using the asp.net Core 2.0 template. I've since moved most of the boilerplate code out in exchange for my own stuff, but am using a mostly similar webpack config and package.json (added a few new packages, nothing major). I'm having an issue where, in my Startup.cs, if I comment out the the lines registering the webpack middleware and configuring HMR, my client will constantly ping this __webpack_hmr resource and error out in the console. The app will still run fine, but the console will constantly have these errors written to it. If I leave the HMR configuration present in Startup.cs, I don't get any errors, but the start up time of the app takes much longer. Both of these issues have me concerned for when this hits productions. Here are the lines I comment out in Startup.cs: ` app.UseWebpackDevMiddleware(new WebpackDevMiddlewareOptions { HotModuleReplacement = false, ReactHotModuleReplacement = false, HotModuleReplacementClientOptions = new Dictionary<string, string> { { "quiet", "true" } } }); ` Here is the log in the console when __webpack_hmr is requested `EventSource's response has a MIME type ("text/html") that is not "text/event-stream". Aborting the connection.` That resource is requested once every ~10 seconds. Another issue is that if I enable HMR (uncommenting those lines from above) webpack will constantly keep rebuilding, instead of only when there is a change to a file.

fergalmoran closed this issue

2025-08-09 17:16:00 +00:00

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Reference: github/JavaScriptServices#363