I have been stock on this error on my project when I add "proxy": "http://localhost:6000"
in my package.json.
This is the error response after yarn start.
Invalid options object. Dev Server has been initialized using an options object that does not match the API schema.
- options.allowedHosts[0] should be a non-empty string. error Command failed with exit code 1. info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.
But everything is fine when I remove the "proxy": "http://localhost:6000".
This is on my package.json:
{
"name": "client",
"version": "0.1.0",
"private": true,
"dependencies": {
"@material-ui/core": "^4.12.3",
"@testing-library/jest-dom": "^5.16.1",
"@testing-library/react": "^12.1.2",
"@testing-library/user-event": "^13.5.0",
"axios": "^0.24.0",
"moment": "^2.29.1",
"react": "^17.0.2",
"react-dom": "^17.0.2",
"react-file-base64": "^1.0.3",
"react-redux": "^7.2.6",
"react-scripts": "5.0.0",
"redux": "^4.1.2",
"redux-thunk": "^2.4.1",
"web-vitals": "^2.1.2"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"eslintConfig": {
"extends": [
"react-app",
"react-app/jest"
]
},
"browserslist": {
"production": [
">0.2%",
"not dead",
"not op_mini all"
],
"development": [
"last 1 chrome version",
"last 1 firefox version",
"last 1 safari version"
]
},
"proxy": "http://localhost:6000"
}
I solved the problem with the http-proxy-middleware solution as others. But to get it working properly, I had to close down my VPN. Same answer as Saeed Kolivand has above. =)
I had the same issue, You can add "allowedHosts": "all" after "proxy": "https://yourdomain" in your package.json. hopefully it solves your problem.
update: the problem was with the company VPN. When I disconnect the VPN, it works normally.
Here is a workaround. Delete "proxy": "http://localhost:6000". Install package http-proxy-middleware with command npm install http-proxy-middleware --save. Create a file setupProxy.js inside your src folder. Add these lines inside:
const { createProxyMiddleware } = require('http-proxy-middleware');
module.exports = function(app) {
app.use(
'/api',
createProxyMiddleware({
target: 'http://localhost:6000',
changeOrigin: true,
})
);
};
Now, run your app. It should work.
The other solutions did not work for me so here's what I found:
This seems to be a CRA bug (security feature?) where allowedHosts gets set to [undefined] because prepareUrls doesn't set lanUrlForConfig when both a host and a proxy are specified. The relevant CRA GitHub issue is here.
If appropriate in your use case (read here to learn more), this can be avoided by creating a .env file and adding DANGEROUSLY_DISABLE_HOST_CHECK=true to it.
A quick solution is to downgrade your webpack version using react-scripts
In the package.json file of your react-app, change the react-scripts version.
Replace
"react-scripts": "5.*",
To
"react-scripts": "4.0.3",
Remove node_modules and install the packages again for your react app.
I had the same problem and josipat's answer worked for me, except I needed to install it as a development dependency. The solution where one saves the following code to src/setUpProxy.js originates from Create React App.
const { createProxyMiddleware } = require('http-proxy-middleware');
module.exports = function(app) {
app.use(
'/api',
createProxyMiddleware({
target: 'http://localhost:5000',
changeOrigin: true,
})
);
};
I have faced the Same Problem.. But when i connected to internet it runs fine...