http-proxy

req = Request , res = Response

you need to log req.body

Cowin public APIs will not work from data centers located outside India. The Heroku data center might be located outside India and hence you are getting this error. You can follow the steps below to check the ip address and location.

Execute this command to get your public facing IP address (from your cloud instance)

Your nginx -V says --with-http_geoip_module=dynamic

so where is your load_module directive?

i added two folders that was missing 'transversal-administration', 'transversal-translation' in the past i have just only: ['app']. the loader in the past load just the app folder

As the error message reveals: You need to specify a Access-Control-Allow-Origin-header in your Server to allow your request across origins. (yea ::3000 and ::8000 are different origins). Modern Browsers will fire a options (pre-flight) request to check the Access-* headers when requesting another origin. You must answer those OPTIONS requests with at least a Access-Control header. Access-Control-Allow-Origin: localhost:3000 should be fine for development.

More about CORS and the Browser OPTIONS Request here:
https://enable-cors.org/
Why is an OPTIONS request sent and can I disable it?

As I was editing the question to provide my proxy config I noticed a potentially unwanted slash in the https-proxy, I removed it and tried the npm install commands:

npm install @fluentui/react@^8.0.0 > "No matching version... found"

npm i @fluentui/react> Worked.

I find interesting that only part of the package download failed making me think that the proxy config was ok and not worrying about it.

I hope this helps someone in the future.

There's not much debug in the question however, to me, it seems that you are using some dependencies outside React's scope, which may potentially block React's hydration process, which may explain the problem described. For example, using Leaflet instead of React's Leaflet or (depending on its implementation) Bootstrap instead of React's Boostrap.

You should be able to change all React-unfriendly modules to React's ones without too much effort and that should fix your problems.

Keep in mind that if your project "work in develop and breaks in build" doesn't mean that your project work or stops working, it just means that is working under certain and specific circumstances. Basically, and summarizing (to avoid extending the answer), gatsby develop uses the browser as an interpreter, where there are, among other things, global objects like window or document. However, gatsby build occurs in the Node server, where at the build time, there are not global objects because there are not even created yet, that the main reason why you may face a different behavior between both scenarios but doesn't mean that the project stopped working magically.

You can read further details in the Overview of Gatsby Build Process.

Another option, linked with blocking React's hydration, is that some component may be blocking that process because of its own behavior. Be careful when using global objects like window or document (or when importing modules that uses it), they use should be always be wrapped inside the following condition, as you can see from the docs:

When referencing window in a React component.

All the plugins are loaded before the Vue instance is ever created and available globally. One solution would be to load any of those packages in specific components rather than on a global level if you don't need them everywhere.

Not sure what can be optimized beyond this.

Also, from this page: https://nuxtjs.org/docs/2.x/configuration-glossary/configuration-plugins

ssr: false will be adapted to mode: 'client' and deprecated in next major release

So, you should not have any ssr in your plugins array.

Thank you all. Cypress flow isn't 100% compatible with standard JS Promise (Wait for an own function (which returns a promise) before tests are executed). After relentless testings, I decided to use a Cypress Custom Command wrapper to wrap my in-house JS library. Though adding an extra layer may seem a little cumbersome. But I am satisfied with the result. Share my code here in case anyone might need it. :)

Cypress Code