Rails server gets response, but localhost page hangs randomly until system reboot - ruby-on-rails

I'm working on a project with a Rails 6.0 backend using webpacker with a React frontend. While working on the frontend with the rails server, my app will sometimes break on Google Chrome, endlessly loading but never even showing the new page title on the tab.
The rails server is receiving the request. It will hit debuggers in the backend and it returns with a 200 status code, but Chrome refuses to load the page while giving no errors or messages indicating what is wrong. This persists even after I restart the rails server, if I restart it on a different port, and if I restart the webpack dev server. I've tried clearing my cache and disabling the cache with devtools, but the only thing that fixes it is rebooting my entire system.
It seems to happen randomly, though I think it may be happening if I refresh the page out of the chrome debugger. I am using ajax for calls to my backend API, not sure if that's possibly a factor.
I've never had this problem before and I'm unsure what it even possibly could be. Does anyone have any idea what might be happening here?

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MVC precompiled site "HTTP Error 403.14 - Forbidden" suddenly appeared after 11 months

I have a precompiled MVC site which runs successfully on multiple servers, and on multiple sites within each server.
One particular site a few days ago suddenly stopped working, returning
HTTP Error 403.14 - Forbidden
I couldn't find anything that would cause it, and rebuilt the site using the same source code as other sites on the same server, in a different folder, and the site ran fine for about 24 hours before once again suddenly experiencing the same error.
There is nothing in the Windows logs (Win 2K12 Server) or in the IIS (6.2) logs (other than confirming the 403). This particular site is running on a Virtual Server in Azure, but plenty of other sites are too, including on the same virtual server using the same source code and settings (other than domain name bindings).
I've currently moved the binding to a different process which is working fine, but I really need to get to the bottom of this in case it suddenly happens again.
I've googled this for days without success. Turning on directory browsing works, but of course not something I can or want to permanently do with MVC. Both home and MVC route requests return the same result, but calls for specific files (eg, a text file in a sub-folder) are successful. That certainly suggests a MVC-specific issue. But I can't work out how to specifically isolate the issue.
Obviously I've reset the application pool, the site itself, and indeed set up a new site using the same application pool (which is working currently, but I'm worried it too will suddenly break at the worst time).
Does anyone have any pointers for working out the main cause, please?

Debug an always pending request IIS MVC

How do I debug an always pending request? This morning something strange started to occur, one request (which should download an PDF file) stopped working. When I reproduce the error I can't see anything in the web browser (tried multiple browsers just in case) or any log files on the server.
All the other requests works fine which makes everything seems strange. I have checked at another server with identical code and there it works just fine, also I have tried to do an iisreset without any success. On the hardware side everything seems great (cpu, ram, disk, network).
We use windows server 2012 and IIS 8
Any ideas on where can I start look for errors?

Rails app on heroku: blank pages on a specific computer

I have a fairly vanilla Rails application on heroku that works fine ... except on my Dad's computer. It is Windows 7, and the site always shows as a blank page. I have checked the following:
Both Chrome, Firefox and IE (latest versions) all exhibit the problem. Web inspector on Chrome and FF shows either a 200 or 304 response code, but blank body.
I have tried clearing the cache.
Curl on his machine successfully downloads the page.
My laptop on his network views the page fine.
His laptop on other networks still exhibits the problem.
His other laptop works fine.
Multiple other machines (5+) work fine.
Server logs show a successful response being served.
Turned off Microsoft Security Essentials.
Turned off the firewall.
I'm stumped. What other debugging steps should I try?
For reference, the site is http://gccc.herokuapp.com/
Solution from twitter: https://www.malwarebytes.org/ picked up a couple of Trojans that were causing issues. I had assumed "Microsoft Security Essentials" was doing this, but I guess that is something different.

How to stop localhost http://localhost from switching to https://localhost

I am writing a web application, and http://localhost:3000 is redirecting to https://localhost:3000
This was not happening a month ago when I finished writing two other applications. I went from working with Sinatra to Rails in the past month, although I have worked with Rails prior without any of these issues.
What can I do to stop this forced switching??
This is probably due your browser, because you have accessed the app in the HTTPS address, it will automatically switch to the HTTPS version of site.
Here you have more information for Firefox, but the solution is to change the settings and set browser.urlbar.autoFill to false. Other option could be to clear the History.

Any ideas how to troubleshoot HTTP Error 400 for MVC/Firefox?

Two clients complains on HTTP Error 400 from Mozilla Firefox 3.6.9. This happens when they open any link - both mvc application and also any static images, which are hosted on Classic application pool without any code.
Exact error message is HTTP Error 400. The request is badly formed
No errors in windows log and application error log. Proxy in browser is set to off.
Other browsers works fine for them.
Any ideas about what could cause such behavior?
For now, i can see only one option - ask them to install Firebug, but this is not really user friendly.
For some reason, cookies was corrupted and this was leading to HTTP 400 error.
After user cleaned cookies for this website he was able to get page.
I still need to investigate what exactly went wrong and find source of this problem but it is clear that I need to review all places where I do cookie creation.

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