React, Heroku, unable to register new user

Question

I migrated server and PostgresQL database to Heroku. However, when I test my new user registration form on Github, nothing happens. I checked the network response in the console, and get 400 Bad request, and "Unable to register" comment, which I set in handleRegister.

console log of error

So it seems that it is communicating with Heroku, but not properly registering. It worked before when everything was stored locally. What am I missing?

Relevant segment of Server API:

const express = require('express');
const bodyParser = require('body-parser');
const bcrypt = require('bcrypt');
const app = express();
const cors = require('cors');
const knex = require('knex')({
    client: 'pg',
    connection: {
        connectionString: process.env.DATABASE_URL,
        ssl: true
    }
});

const register = require('./controllers/register');

app.use(bodyParser.json());
app.use(cors());

app.get('/', (req, res) => {res.send("It's working!")})
app.post('/register', (req, res) => {register.handleRegister(req, res, knex, bcrypt)})

const PORT = process.env.PORT || 3000;
app.listen(PORT, err => {
  if(err) throw err;
  console.log("Server running");
});

Server register controller:

const handleRegister = (req, res, knex, bcrypt) => {
    const { email, name, password} = req.body;
    if (!email || !name || !password) {
        return res.status(400).json('invalid form registration');
    }
    const salt = bcrypt.genSaltSync(saltRounds);
    const hash = bcrypt.hashSync(password, salt);
    knex.transaction(trx => {
        trx.insert({
            hash: hash,
            email: email            
        })
        .into('login')
        .returning('email')
        .then(loginEmail => {
            return trx('users')
            .returning('*')
            .insert({
                email: email,
                name: name,
                joined: new Date()
            })
            .then(user => {
                res.json(user[0]);
            })
        })
        .then(trx.commit)
        .catch(trx.rollback)
    })  
    .catch(err => res.status(400).json('Unable to register'));
}

Thanks in advance!