ERR_STREAM_WRITE_AFTER_END how to solve?

Question

Node.js

During development, everything worked, when I launched Ubuntu on the VPS, an error occurred in the console

events.js:292                                                                    
      throw er; // Unhandled 'error' event                                       
      ^                                                                          
                                                                                 
Error [ERR_STREAM_WRITE_AFTER_END]: write after end                              
    at writeAfterEnd (_http_outgoing.js:643:15)                                  
    at ServerResponse.end (_http_outgoing.js:763:7)                              
    at /home/puryga/node/server.js:1334:29                                       
    at FSReqCallback.readFileAfterClose [as oncomplete] (internal/fs/read_file_co
ntext.js:63:3)                                                                   
Emitted 'error' event on ServerResponse instance at:                             
    at writeAfterEndNT (_http_outgoing.js:702:7)                                 
    at processTicksAndRejections (internal/process/task_queues.js:85:21) {       
  code: 'ERR_STREAM_WRITE_AFTER_END'                                             
}

Code snippet referenced by the error

let filePath = path.join(process.cwd(), '/public', pathName)

    fs.readFile(filePath, 'utf-8', (err, html) => {
        if(err) {
            nopath = path.join(process.cwd(), '/', 'nopath.html')

            fs.readFile(nopath, (err , html) => {
                if(!err) {

                    res.writeHead(404, {'Content-Type': 'text/html'})
                    res.end(html)

                }
                else{

                    let text = "404 file open error"
                    res.writeHead(404, {'Content-Type': 'text/plain'})
                    res.end(text)

                }
            })
        }
        else{

            for (let it in mimeTypes) {
                if (mimeTypes.hasOwnProperty(it)) {
                    if (ext == it) {

                        res.writeHead(200, {'Content-Type': mimeTypes[ext]})
                        filePath = path.join(process.cwd(), '/public', pathName)

                        fs.readFile(filePath, (err , content) => {
                            if(!err) {

                                res.writeHead(200, {'Content-Type': mimeTypes[ext]})
                                res.end(content)

                            }
                            else{

                                res.writeHead(404, {'Content-Type': 'text/plain'})
                                res.end()

                            }
                        })
                    } else if (ext == '.html') {

                        const content = require(filePath)
                        let p = ''
                        if (req.url.split('?')[1] != '') {
                            p = req.url.split('?')[1]
                        }
                        res.writeHead(200, {'Content-Type': 'text/html'})
                        res.end(content.getContent(SESSION_KEY, p))

                    }
                }
            }
        }
    })
})

In short - in this fragment, depending on the url requested from the client, different files are given.