我正在尝试在Heroku上启动一个网站。它是用React，Flask和MySQL构建的。生成过程成功完成，但是当我打开网站并显示以下消息“在服务器上找不到所请求的URL。如果您手动输入URL，请检查拼写，然后重试。”，则显示404 Not Found错误。
这是下面的部分日志。我通过将服务器文件放在api文件夹中以及将前端文件放在client文件夹中来分离前端和后端。 api和client文件夹位于同一文件夹中。不好意思，很抱歉。我是新手。
2020-09-15T11:55:14.830445+00:00 app[web.1]: gunicorn.errors.HaltServer: <HaltServer 'Worker failed to boot.' 3>
2020-09-15T11:55:14.964408+00:00 heroku[web.1]: Process exited with status 1
2020-09-15T11:55:15.008210+00:00 heroku[web.1]: State changed from starting to crashed
2020-09-15T14:57:57.243316+00:00 heroku[web.1]: State changed from crashed to starting
2020-09-15T14:58:05.000000+00:00 app[api]: Build succeeded
2020-09-15T14:58:08.708626+00:00 heroku[web.1]: Starting process with command `gunicorn api.server:app`
2020-09-15T14:58:11.325367+00:00 app[web.1]: [2020-09-15 14:58:11 +0000] [4] [INFO] Starting gunicorn 20.0.4
2020-09-15T14:58:11.326031+00:00 app[web.1]: [2020-09-15 14:58:11 +0000] [4] [INFO] Listening at: http://0.0.0.0:16492 (4)
2020-09-15T14:58:11.326146+00:00 app[web.1]: [2020-09-15 14:58:11 +0000] [4] [INFO] Using worker: sync
2020-09-15T14:58:11.330221+00:00 app[web.1]: [2020-09-15 14:58:11 +0000] [10] [INFO] Booting worker with pid: 10
2020-09-15T14:58:11.352448+00:00 app[web.1]: [2020-09-15 14:58:11 +0000] [11] [INFO] Booting worker with pid: 11
2020-09-15T14:58:11.415401+00:00 app[web.1]: [2020-09-15 14:58:11 +0000] [12] [INFO] Booting worker with pid: 12
2020-09-15T14:58:11.724701+00:00 heroku[web.1]: State changed from starting to up
2020-09-15T14:58:47.373372+00:00 heroku[router]: at=info method=GET path="/" host=uiuc-reddit.herokuapp.com request_id=b851bd84-92ca-4105-81a4-cfd98bcf8523 fwd="99.127.221.203" dyno=web.1 connect=1ms service=7ms status=404 bytes=432 protocol=https
2020-09-15T14:58:47.375950+00:00 app[web.1]: 10.102.182.112 - - [15/Sep/2020:14:58:47 +0000] "GET / HTTP/1.1" 404 232 "https://dashboard.heroku.com/" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/85.0.4183.102 Safari/537.36"
cc
Procfile
web: gunicorn api.server:app
Server.py
from flask import Flask, jsonify, request, json, make_response
from flask_mysqldb import MySQL
from datetime import datetime
from flask_cors import CORS
from flask_jwt_extended import (JWTManager, create_access_token)
from flask_bcrypt import Bcrypt
from datetime import datetime
app = Flask(__name__)
app.config['MYSQL_HOST'] = 'localhost'
app.config['MYSQL_USER'] = 'root'
app.config['MYSQL_PASSWORD'] = '1234'
app.config['MYSQL_DB'] = 'reddit'
app.config['MYSQL_CURSORCLASS'] = 'DictCursor'
app.config['JWT_SECRET_KEY'] = 't1NP63m4wnBg6nyHYKf2c2TpCOGI2nss'
mysql = MySQL(app)
bcrypt = Bcrypt(app)
jwt = JWTManager(app)
CORS(app)
...codes below