Thank you Jake Foraker ! That took care of the GET error, however my original datas are still not showing and I am still getting this: POST https://fierce-sierra-67905.herokuapp.com/ 404 (Not Found) My connection.js: var mongoose = require ( "mongoose" ) mongoose.connect( "mongodb://localhost/projectbook" , (err) => { if (err) { console .log(err) } else { console .log( "MongoDB is Connected!" ) } }) module .exports = mongoose Package.json: ... "scripts" : { "start" : "cross-env NODE_ENV=production MONGO_URL=mongodb://localhost/projectbook node index.js" , "start-dev" : "nf start -p 3000" , "build" : "react-scripts build" , "test" : "react-scripts/test.js --env=jsdom" , "eject" : "react-scripts eject" }, ... "testEnvironment" : "node" , "testURL" : "http://localhost" , ... Am I supposed to deploy my mongodb on a separate heroku deployment? Please pardon my ignorance, Thanks again for your help!

Hello! I deployed my MERN app to Heroku, it is rendering properly and my third-party API search function works well. However, it seems like my GET and POST methods to add new data is not working now. I also lost the datas that were originally stored on my database. I got the below errors: GET https://localhost:3001/api/projects net::ERR_CONNECTION_REFUSED OPTIONS https://localhost:3001/api/projects net::ERR_CONNECTION_REFUSED Uncaught (in promise) Error: Network Error at createError (createError.js:15) at XMLHttpRequest.handleError (xhr.js:87) Originally I had the Mixed-Content error and I fixed that by adding the below to my index.html's head section: <meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests"> Here is link to my app: https://fierce-sierra-67905.herokuapp.com/ This is my first time deploying MERN app on Heroku and have struggled for a while. Any help would be much appreciated!