proxy error: could not proxy request /api/register from localhost:3000 to http://localhost:3001/ code example

Example 1: react proxy error: could not proxy request from localhost:3000 to http localhost:5000 econnreset

"start": "./node_modules/.bin/concurrently \"./node_modules/.bin/nodemon\" \"npm run client\"",

Example 2: react proxy error: could not proxy request from localhost:3000 to http localhost:5000 econnreset

"start": "./node_modules/.bin/concurrently \"npm run server\" \"npm run client\"",