Typescript React.Js File Upload Event Ts2322 Error

I know this is not the optimal solution.But here is complete back-end and front-end code for those who are trying to accomplish same task using .net core,react.js and typescript.

Here is my tsx file note that I commented file property in my interface and made it public property.

import * as React from 'react';
import { RouteComponentProps } from 'react-router';
import { Button, Form, FormGroup, Label, Input, FormText } from 'reactstrap';
import ListGroup from 'reactstrap/lib/ListGroup';

interface UploadContainerState {

    tcknVkn: number;
    proclamationYear: number;
    alertVisible: boolean;

    //file: FileList
}
export default class UploadContainer extends React.Component<{}, UploadContainerState> {
    public file: File;
    constructor(props: any) {
        super(props);
        this.state = {
            proclamationYear: 0,
            tcknVkn: 0,
            alertVisible: false
        }
        this.proclamationYearChange = this.proclamationYearChange.bind(this);
        this.tcknVknChange = this.tcknVknChange.bind(this);
        this.uploadFile = this.uploadFile.bind(this);
        this.fileChange = this.fileChange.bind(this);

    }
    proclamationYearChange(event: any) {
        this.setState({ proclamationYear: event.target.value });
    }
    tcknVknChange(event: any) {
        this.setState({ tcknVkn: event.target.value });
    }
    onDismiss() {
        this.setState({ alertVisible: false });
    }

    fileChange(event: any) {
        this.file = event.target.files[0];
        event.preventDefault();

    }

    render() {
        return (
            <div>

                <form onSubmit={this.uploadFile} className="uploader" encType="multipart/form-data" >
                    <FormGroup>
                        <Label for="proclamationYear">Year</Label>
                        <Input type="text" name="proclamationYear" id="proclamationYear"  onChange={this.proclamationYearChange} value={this.state.proclamationYear} />
                    </FormGroup>
                    <FormGroup>
                        <Label for="tcknVkn">Tckn/Vkn</Label>
                        <Input type="text" name="tcknVkn" id="tcknVkn"  onChange={this.tcknVknChange} value={this.state.tcknVkn} />
                    </FormGroup>

                    <input type="file" name="file" accept=".pdf" className="upload-file" onChange={this.fileChange} />
                    <input type="submit" value="Submit" />
                </form>
            </div>
        );
    }
    uploadFile(event: any) {
        let that = this;
        event.preventDefault();
        let formData = new FormData();
        formData.append('file', this.file);
        formData.append('tcknVkn', event.target.tcknVkn.value);
        formData.append('proclamationYear', event.target.proclamationYear.value);
        fetch("ProposalData/UploadFile", {
            method: 'POST',
            credentials: 'include',
            headers: {
                'Accept': 'application/json, */*',
            },
            body: formData
        })
            .then(handleErrors)
            .then(function (response) {
                console.log("ok");
            }).catch(function (error) {

                console.log(error);
            });
    }
};
function handleErrors(response: any) {
    if (!response.ok) {
        throw Error(response.statusText);
    }
    return response;
}

Here is my controller

public class FileUploadModel
{
    public string ProclamationYear { get; set; }
    public string TcknVkn { get; set; }
    public IFormFile File { get; set; }
}
 [HttpPost]
        public async Task<IActionResult> UploadFile([FromForm]FileUploadModel vm)
        {
            var file = vm.File;

You have a mismatch in value property type. Expected is string | number | string[] | undefined while you are passing in FileList

You cannot set value of file input due to security reason. The only way to set file input's value is via user action in browser. Remove value={this.state.file} and it will compile.

Besides that, the type of the state field should be File