Error deploying MERN application to Heroku

Question

The app successfully deploys but when I try to open the app, I get the following error:

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Application error An error occurred in the application and your page could not be served. If you are the application owner, check your logs for details. You can do this from the Heroku CLI with the command heroku logs --tail

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I ran -heroku logs --tail and I get the following:

deons-mbp:shrinkURL deonchoi$ heroku logs --tail
2019-12-13T02:59:25.356685+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2019-12-13T02:59:25.356952+00:00 app[web.1]: npm ERR! errno 1
2019-12-13T02:59:25.357905+00:00 app[web.1]: npm ERR! backend@1.0.0 start: `node server.js`
2019-12-13T02:59:25.358057+00:00 app[web.1]: npm ERR! Exit status 1
2019-12-13T02:59:25.358220+00:00 app[web.1]: npm ERR!
2019-12-13T02:59:25.358348+00:00 app[web.1]: npm ERR! Failed at the backend@1.0.0 start script.
2019-12-13T02:59:25.358480+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2019-12-13T02:59:25.362742+00:00 app[web.1]: 
2019-12-13T02:59:25.362837+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2019-12-13T02:59:25.362931+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2019-12-13T02_59_25_359Z-debug.log
2019-12-13T02:59:25.446611+00:00 heroku[web.1]: State changed from starting to crashed
2019-12-13T02:59:25.422394+00:00 heroku[web.1]: Process exited with status 1
2019-12-13T03:00:38.195196+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrinkurlapp.herokuapp.com request_id=99378587-a922-4ad8-8445-aca15eba268a fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:00:38.710170+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrinkurlapp.herokuapp.com request_id=ba6a84fe-9a4b-433d-a00d-1a6231e0317c fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:00:49.612623+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrinkurlapp.herokuapp.com request_id=7fb228bc-9e62-4526-a51e-feff9631e266 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:00:50.201204+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrinkurlapp.herokuapp.com request_id=ada57278-8d33-4569-b3e3-bad6b136a234 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:03:11.014926+00:00 heroku[web.1]: State changed from crashed to starting
2019-12-13T03:03:13.149581+00:00 heroku[web.1]: Starting process with command `npm start`
2019-12-13T03:03:15.545496+00:00 app[web.1]: 
2019-12-13T03:03:15.545520+00:00 app[web.1]: > backend@1.0.0 start /app
2019-12-13T03:03:15.545522+00:00 app[web.1]: > node server.js
2019-12-13T03:03:15.545524+00:00 app[web.1]: 
2019-12-13T03:03:16.082886+00:00 app[web.1]: 
2019-12-13T03:03:16.082936+00:00 app[web.1]: /app/node_modules/mongoose/lib/connection.js:541
2019-12-13T03:03:16.082939+00:00 app[web.1]: throw new MongooseError('The `uri` parameter to `openUri()` must be a ' +
2019-12-13T03:03:16.082942+00:00 app[web.1]: ^
2019-12-13T03:03:16.086177+00:00 app[web.1]: Error [MongooseError]: The `uri` parameter to `openUri()` must be a string, got "undefined". Make sure the first parameter to `mongoose.connect()` or `mongoose.createConnection()` is a string.
2019-12-13T03:03:16.086180+00:00 app[web.1]: at new MongooseError (/app/node_modules/mongoose/lib/error/mongooseError.js:10:11)
2019-12-13T03:03:16.086183+00:00 app[web.1]: at NativeConnection.Connection.openUri (/app/node_modules/mongoose/lib/connection.js:541:11)
2019-12-13T03:03:16.086185+00:00 app[web.1]: at Mongoose.connect (/app/node_modules/mongoose/lib/index.js:328:15)
2019-12-13T03:03:16.086187+00:00 app[web.1]: at Object.<anonymous> (/app/server.js:16:10)
2019-12-13T03:03:16.086189+00:00 app[web.1]: at Module._compile (internal/modules/cjs/loader.js:959:30)
2019-12-13T03:03:16.086191+00:00 app[web.1]: at Object.Module._extensions..js (internal/modules/cjs/loader.js:995:10)
2019-12-13T03:03:16.086193+00:00 app[web.1]: at Module.load (internal/modules/cjs/loader.js:815:32)
2019-12-13T03:03:16.086195+00:00 app[web.1]: at Function.Module._load (internal/modules/cjs/loader.js:727:14)
2019-12-13T03:03:16.086197+00:00 app[web.1]: at Function.Module.runMain (internal/modules/cjs/loader.js:1047:10)
2019-12-13T03:03:16.086200+00:00 app[web.1]: at internal/main/run_main_module.js:17:11 {
2019-12-13T03:03:16.086203+00:00 app[web.1]: message: 'The `uri` parameter to `openUri()` must be a string, got "undefined". Make sure the first parameter to `mongoose.connect()` or `mongoose.createConnection()` is a string.',
2019-12-13T03:03:16.086205+00:00 app[web.1]: name: 'MongooseError'
2019-12-13T03:03:16.086207+00:00 app[web.1]: }
2019-12-13T03:03:16.092626+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2019-12-13T03:03:16.092996+00:00 app[web.1]: npm ERR! errno 1
2019-12-13T03:03:16.094046+00:00 app[web.1]: npm ERR! backend@1.0.0 start: `node server.js`
2019-12-13T03:03:16.094306+00:00 app[web.1]: npm ERR! Exit status 1
2019-12-13T03:03:16.094539+00:00 app[web.1]: npm ERR!
2019-12-13T03:03:16.094740+00:00 app[web.1]: npm ERR! Failed at the backend@1.0.0 start script.
2019-12-13T03:03:16.094919+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2019-12-13T03:03:16.104750+00:00 app[web.1]: 
2019-12-13T03:03:16.105020+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2019-12-13T03:03:16.105275+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2019-12-13T03_03_16_095Z-debug.log
2019-12-13T03:03:16.178860+00:00 heroku[web.1]: State changed from starting to crashed
2019-12-13T03:03:16.164865+00:00 heroku[web.1]: Process exited with status 1
2019-12-13T03:03:24.145385+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrinkurlapp.herokuapp.com request_id=ca564a1c-156c-484a-9354-ce243b3b1ed5 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:03:24.586560+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrinkurlapp.herokuapp.com request_id=bb81ead2-cd04-462f-9ab9-64b84d9238bb fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:08:40.000000+00:00 app[api]: Build started by user deon.choi@gmail.com
2019-12-13T03:08:55.468949+00:00 app[api]: Deploy 67508aba by user deon.choi@gmail.com
2019-12-13T03:08:55.468949+00:00 app[api]: Release v4 created by user deon.choi@gmail.com
2019-12-13T03:08:55.741086+00:00 heroku[web.1]: State changed from crashed to starting
2019-12-13T03:08:56.000000+00:00 app[api]: Build succeeded
2019-12-13T03:08:57.971434+00:00 heroku[web.1]: Starting process with command `npm start`
2019-12-13T03:08:59.915432+00:00 app[web.1]: 
2019-12-13T03:08:59.915464+00:00 app[web.1]: > backend@1.0.0 start /app
2019-12-13T03:08:59.915467+00:00 app[web.1]: > node server.js
2019-12-13T03:08:59.915470+00:00 app[web.1]: 
2019-12-13T03:09:00.319828+00:00 app[web.1]: 
2019-12-13T03:09:00.319851+00:00 app[web.1]: /app/node_modules/mongoose/lib/connection.js:541
2019-12-13T03:09:00.319854+00:00 app[web.1]: throw new MongooseError('The `uri` parameter to `openUri()` must be a ' +
2019-12-13T03:09:00.319857+00:00 app[web.1]: ^
2019-12-13T03:09:00.322625+00:00 app[web.1]: Error [MongooseError]: The `uri` parameter to `openUri()` must be a string, got "undefined". Make sure the first parameter to `mongoose.connect()` or `mongoose.createConnection()` is a string.
2019-12-13T03:09:00.322629+00:00 app[web.1]: at new MongooseError (/app/node_modules/mongoose/lib/error/mongooseError.js:10:11)
2019-12-13T03:09:00.322632+00:00 app[web.1]: at NativeConnection.Connection.openUri (/app/node_modules/mongoose/lib/connection.js:541:11)
2019-12-13T03:09:00.322634+00:00 app[web.1]: at Mongoose.connect (/app/node_modules/mongoose/lib/index.js:328:15)
2019-12-13T03:09:00.322636+00:00 app[web.1]: at Object.<anonymous> (/app/server.js:18:10)
2019-12-13T03:09:00.322639+00:00 app[web.1]: at Module._compile (internal/modules/cjs/loader.js:959:30)
2019-12-13T03:09:00.322641+00:00 app[web.1]: at Object.Module._extensions..js (internal/modules/cjs/loader.js:995:10)
2019-12-13T03:09:00.322644+00:00 app[web.1]: at Module.load (internal/modules/cjs/loader.js:815:32)
2019-12-13T03:09:00.322646+00:00 app[web.1]: at Function.Module._load (internal/modules/cjs/loader.js:727:14)
2019-12-13T03:09:00.322648+00:00 app[web.1]: at Function.Module.runMain (internal/modules/cjs/loader.js:1047:10)
2019-12-13T03:09:00.322651+00:00 app[web.1]: at internal/main/run_main_module.js:17:11 {
2019-12-13T03:09:00.322654+00:00 app[web.1]: message: 'The `uri` parameter to `openUri()` must be a string, got "undefined". Make sure the first parameter to `mongoose.connect()` or `mongoose.createConnection()` is a string.',
2019-12-13T03:09:00.322657+00:00 app[web.1]: name: 'MongooseError'
2019-12-13T03:09:00.322660+00:00 app[web.1]: }
2019-12-13T03:09:00.331200+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2019-12-13T03:09:00.331487+00:00 app[web.1]: npm ERR! errno 1
2019-12-13T03:09:00.333012+00:00 app[web.1]: npm ERR! backend@1.0.0 start: `node server.js`
2019-12-13T03:09:00.333312+00:00 app[web.1]: npm ERR! Exit status 1
2019-12-13T03:09:00.333487+00:00 app[web.1]: npm ERR!
2019-12-13T03:09:00.333633+00:00 app[web.1]: npm ERR! Failed at the backend@1.0.0 start script.
2019-12-13T03:09:00.333752+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2019-12-13T03:09:00.341621+00:00 app[web.1]: 
2019-12-13T03:09:00.341770+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2019-12-13T03:09:00.341887+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2019-12-13T03_09_00_334Z-debug.log
2019-12-13T03:09:00.424560+00:00 heroku[web.1]: State changed from starting to crashed
2019-12-13T03:09:00.403174+00:00 heroku[web.1]: Process exited with status 1
2019-12-13T03:09:01.483310+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrinkurlapp.herokuapp.com request_id=79b75979-00fa-4994-a5d1-4f73c5841172 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:09:02.191776+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrinkurlapp.herokuapp.com request_id=93cf4327-3365-4174-a2df-7545952b00a6 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:09:03.076316+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrinkurlapp.herokuapp.com request_id=a2492372-c679-4144-acd1-7956692ad1e0 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:09:03.469741+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrinkurlapp.herokuapp.com request_id=d14e6638-96d5-4f19-8701-03ab766969fc fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:09:47.050280+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=shrinkurlapp.herokuapp.com request_id=287c82b4-b3a6-42cc-81c5-ed97f310f7d3 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https
2019-12-13T03:09:47.349496+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=shrinkurlapp.herokuapp.com request_id=b1ced555-16fd-4255-92be-486d0917aff1 fwd="98.210.22.60" dyno= connect= service= status=503 bytes= protocol=https

I thought the issue was with my mongoose.connect() statement but it seems as if that is not the case. Here is my server.js express file:

const express = require('express');
const cors = require('cors');
const mongoose = require('mongoose');
const cookieParser = require('cookie-parser');
const path = require('path');

require('dotenv').config();

const app = express();
const port = process.env.PORT || 3000;

app.use(cors());
app.use(express.json());
app.use(cookieParser());

const dbURI = process.env.DB_CONNECTION;

mongoose.connect(dbURI, {useNewUrlParser: true, useUnifiedTopology: true});

const connection = mongoose.connection;
connection.once('open', () => {
    console.log('MongoDB database connection established successfully');
});

const urlsRouter = require('./routes/urls');
const redirectRouter = require('./routes/index');
const authRoute = require('./routes/auth');

app.use('/api/urls', urlsRouter);
app.use('/api/user', authRoute);
app.use('/api', redirectRouter);

app.use(express.static(path.join(__dirname, 'build')));

app.get('*', (req, res) => {
    res.sendFile(path.resolve(__dirname, 'build', 'index.html'));
});

app.listen(port, () => {
    console.log(`Server is running on port ${port}`)
});

Answer 1

refer the following to set environment variable to be used:

https://devcenter.heroku.com/articles/config-vars

The env variable that requires to be set is : DB_CONNECTION