I have created an app that upload some files and than send me object like that
{"name":"MEHMET SAYIN CV - 10_2021.pdf","type":"application/pdf","size":99771}
I used multer to handle uploading files. When I upload it to heroku I failed.I want to share the logs related.
2021-10-15T15:51:02.457409+00:00 app[api]: Deploy 6e984f86 by user sayinmehmet47@gmail.com
2021-10-15T15:51:02.457409+00:00 app[api]: Release v11 created by user sayinmehmet47@gmail.com
2021-10-15T15:51:03.599539+00:00 heroku[web.1]: State changed from crashed to starting
2021-10-15T15:51:05.000000+00:00 app[api]: Build succeeded
2021-10-15T15:51:05.698098+00:00 heroku[web.1]: Starting process with command `npm start`
2021-10-15T15:51:06.737506+00:00 app[web.1]:
2021-10-15T15:51:06.737526+00:00 app[web.1]: > file_metadata@0.0.1 start /app
2021-10-15T15:51:06.737527+00:00 app[web.1]: > node server.js
2021-10-15T15:51:06.737527+00:00 app[web.1]:
2021-10-15T15:51:07.036041+00:00 app[web.1]: connected
2021-10-15T15:51:07.068246+00:00 app[web.1]: /app/node_modules/mkdirp/index.js:91
2021-10-15T15:51:07.068247+00:00 app[web.1]: throw err0;
2021-10-15T15:51:07.068248+00:00 app[web.1]: ^
2021-10-15T15:51:07.068248+00:00 app[web.1]:
2021-10-15T15:51:07.068248+00:00 app[web.1]: Error: EROFS: read-only file system, mkdir '/public'
2021-10-15T15:51:07.068249+00:00 app[web.1]: at Object.mkdirSync (fs.js:1013:3)
2021-10-15T15:51:07.068249+00:00 app[web.1]: at sync (/app/node_modules/mkdirp/index.js:72:13)
2021-10-15T15:51:07.068250+00:00 app[web.1]: at sync (/app/node_modules/mkdirp/index.js:78:24)
2021-10-15T15:51:07.068250+00:00 app[web.1]: at Function.sync (/app/node_modules/mkdirp/index.js:78:24)
2021-10-15T15:51:07.068250+00:00 app[web.1]: at new DiskStorage (/app/node_modules/multer/storage/disk.js:21:12)
2021-10-15T15:51:07.068251+00:00 app[web.1]: at module.exports (/app/node_modules/multer/storage/disk.js:65:10)
2021-10-15T15:51:07.068251+00:00 app[web.1]: at new Multer (/app/node_modules/multer/index.js:15:20)
2021-10-15T15:51:07.068252+00:00 app[web.1]: at multer (/app/node_modules/multer/index.js:95:12)
2021-10-15T15:51:07.068252+00:00 app[web.1]: at Object.<anonymous> (/app/api/files.js:4:16)
2021-10-15T15:51:07.068252+00:00 app[web.1]: at Module._compile (internal/modules/cjs/loader.js:1085:14) {
2021-10-15T15:51:07.068253+00:00 app[web.1]: errno: -30,
2021-10-15T15:51:07.068253+00:00 app[web.1]: syscall: 'mkdir',
2021-10-15T15:51:07.068253+00:00 app[web.1]: code: 'EROFS',
2021-10-15T15:51:07.068254+00:00 app[web.1]: path: '/public'
2021-10-15T15:51:07.068254+00:00 app[web.1]: }
2021-10-15T15:51:07.079497+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2021-10-15T15:51:07.079732+00:00 app[web.1]: npm ERR! errno 1
2021-10-15T15:51:07.083831+00:00 app[web.1]: npm ERR! file_metadata@0.0.1 start: `node server.js`
2021-10-15T15:51:07.083871+00:00 app[web.1]: npm ERR! Exit status 1
2021-10-15T15:51:07.083924+00:00 app[web.1]: npm ERR!
2021-10-15T15:51:07.083988+00:00 app[web.1]: npm ERR! Failed at the file_metadata@0.0.1 start script.
2021-10-15T15:51:07.083989+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2021-10-15T15:51:07.089384+00:00 app[web.1]:
2021-10-15T15:51:07.089446+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2021-10-15T15:51:07.089472+00:00 app[web.1]: npm ERR! /app/.npm/_logs/2021-10-15T15_51_07_084Z-debug.log
2021-10-15T15:51:07.196350+00:00 heroku[web.1]: Process exited with status 1
2021-10-15T15:51:07.347289+00:00 heroku[web.1]: State changed from starting to crashed
2021-10-15T15:51:12.784398+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=filedownl12.herokuapp.com request_id=fe098106-1546-4b7c-9b8c-fefe790dfae7 fwd="77.49.34.161" dyno= connect= service= status=503 bytes= protocol=https
2021-10-15T15:51:13.747221+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=filedownl12.herokuapp.com request_id=8173d073-97c1-45e1-afab-c3b2da397e12 fwd="77.49.34.161" dyno= connect= service= status=503 bytes= protocol=https
2021-10-15T16:04:45.000000+00:00 app[api]: Build started by user sayinmehmet47@gmail.com
2021-10-15T16:05:21.465576+00:00 app[api]: Deploy 1f51e389 by user sayinmehmet47@gmail.com
2021-10-15T16:05:21.465576+00:00 app[api]: Release v12 created by user sayinmehmet47@gmail.com
2021-10-15T16:05:23.278268+00:00 heroku[web.1]: State changed from crashed to starting
2021-10-15T16:05:24.000000+00:00 app[api]: Build succeeded
2021-10-15T16:05:26.141343+00:00 heroku[web.1]: Starting process with command `node ./server.js`
2021-10-15T16:05:27.754473+00:00 app[web.1]: connected
2021-10-15T16:05:27.819924+00:00 app[web.1]: /app/node_modules/mkdirp/index.js:91
2021-10-15T16:05:27.819926+00:00 app[web.1]: throw err0;
2021-10-15T16:05:27.819926+00:00 app[web.1]: ^
2021-10-15T16:05:27.819927+00:00 app[web.1]:
2021-10-15T16:05:27.819927+00:00 app[web.1]: Error: EROFS: read-only file system, mkdir '/public'
2021-10-15T16:05:27.819928+00:00 app[web.1]: at Object.mkdirSync (fs.js:1013:3)
2021-10-15T16:05:27.819928+00:00 app[web.1]: at sync (/app/node_modules/mkdirp/index.js:72:13)
2021-10-15T16:05:27.819928+00:00 app[web.1]: at sync (/app/node_modules/mkdirp/index.js:78:24)
2021-10-15T16:05:27.819929+00:00 app[web.1]: at Function.sync (/app/node_modules/mkdirp/index.js:78:24)
2021-10-15T16:05:27.819929+00:00 app[web.1]: at new DiskStorage (/app/node_modules/multer/storage/disk.js:21:12)
2021-10-15T16:05:27.819930+00:00 app[web.1]: at module.exports (/app/node_modules/multer/storage/disk.js:65:10)
2021-10-15T16:05:27.819930+00:00 app[web.1]: at new Multer (/app/node_modules/multer/index.js:15:20)
2021-10-15T16:05:27.819931+00:00 app[web.1]: at multer (/app/node_modules/multer/index.js:95:12)
2021-10-15T16:05:27.819931+00:00 app[web.1]: at Object.<anonymous> (/app/api/files.js:4:16)
2021-10-15T16:05:27.819931+00:00 app[web.1]: at Module._compile (internal/modules/cjs/loader.js:1085:14) {
2021-10-15T16:05:27.819932+00:00 app[web.1]: errno: -30,
2021-10-15T16:05:27.819932+00:00 app[web.1]: syscall: 'mkdir',
2021-10-15T16:05:27.819932+00:00 app[web.1]: code: 'EROFS',
2021-10-15T16:05:27.819933+00:00 app[web.1]: path: '/public'
2021-10-15T16:05:27.819933+00:00 app[web.1]: }
2021-10-15T16:05:27.968565+00:00 heroku[web.1]: Process exited with status 1
2021-10-15T16:05:28.098649+00:00 heroku[web.1]: State changed from starting to crashed
2021-10-15T16:05:28.136896+00:00 heroku[web.1]: State changed from crashed to starting
2021-10-15T16:05:30.375434+00:00 heroku[web.1]: Starting process with command `node ./server.js`
2021-10-15T16:05:32.063799+00:00 app[web.1]: connected
2021-10-15T16:05:32.108031+00:00 app[web.1]: /app/node_modules/mkdirp/index.js:91
2021-10-15T16:05:32.108033+00:00 app[web.1]: throw err0;
2021-10-15T16:05:32.108033+00:00 app[web.1]: ^
2021-10-15T16:05:32.108033+00:00 app[web.1]:
2021-10-15T16:05:32.108034+00:00 app[web.1]: Error: EROFS: read-only file system, mkdir '/public'
2021-10-15T16:05:32.108034+00:00 app[web.1]: at Object.mkdirSync (fs.js:1013:3)
2021-10-15T16:05:32.108035+00:00 app[web.1]: at sync (/app/node_modules/mkdirp/index.js:72:13)
2021-10-15T16:05:32.108035+00:00 app[web.1]: at sync (/app/node_modules/mkdirp/index.js:78:24)
2021-10-15T16:05:32.108035+00:00 app[web.1]: at Function.sync (/app/node_modules/mkdirp/index.js:78:24)
2021-10-15T16:05:32.108036+00:00 app[web.1]: at new DiskStorage (/app/node_modules/multer/storage/disk.js:21:12)
2021-10-15T16:05:32.108036+00:00 app[web.1]: at module.exports (/app/node_modules/multer/storage/disk.js:65:10)
2021-10-15T16:05:32.108036+00:00 app[web.1]: at new Multer (/app/node_modules/multer/index.js:15:20)
2021-10-15T16:05:32.108037+00:00 app[web.1]: at multer (/app/node_modules/multer/index.js:95:12)
2021-10-15T16:05:32.108037+00:00 app[web.1]: at Object.<anonymous> (/app/api/files.js:4:16)
2021-10-15T16:05:32.108037+00:00 app[web.1]: at Module._compile (internal/modules/cjs/loader.js:1085:14) {
2021-10-15T16:05:32.108038+00:00 app[web.1]: errno: -30,
2021-10-15T16:05:32.108041+00:00 app[web.1]: syscall: 'mkdir',
2021-10-15T16:05:32.108041+00:00 app[web.1]: code: 'EROFS',
2021-10-15T16:05:32.108041+00:00 app[web.1]: path: '/public'
2021-10-15T16:05:32.108041+00:00 app[web.1]: }
2021-10-15T16:05:32.267952+00:00 heroku[web.1]: Process exited with status 1
2021-10-15T16:05:32.695933+00:00 heroku[web.1]: State changed from starting to crashed
2021-10-15T16:05:33.707024+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=filedownl12.herokuapp.com request_id=c9fdfd08-1b36-450e-a4de-fb65785677a4 fwd="77.49.34.161" dyno= connect= service= status=503 bytes= protocol=https
2021-10-15T16:05:34.925481+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=filedownl12.herokuapp.com request_id=3aca34c2-47e0-4f99-9884-13b91ed25f99 fwd="77.49.34.161" dyno= connect= service= status=503 bytes= protocol=https
2021-10-15T16:13:09.486503+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=filedownl12.herokuapp.com request_id=e41ba396-2172-4804-a573-0fafc1a2c47b fwd="77.49.34.161" dyno= connect= service= status=503 bytes= protocol=https
2021-10-15T16:13:10.694600+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/favicon.ico" host=filedownl12.herokuapp.com request_id=4ef46b32-012c-43b2-8342-0a0637d5a29b fwd="77.49.34.161" dyno= connect= service= status=503 bytes= protocol=https
I also tried to be sure if I set the variables for MONGO_URI,I also set them. Also I created a procfile and write inside it
web: node ./server.js
But it didnt works. I lastly want to share my directories picture. 
This also my github link that I donwloaded the project .