Unprocessable Resource Fetching Data from API

In an attempt to connect my reactjs frontend to a nodejs/expressjs API, Im receiving an error in console:

POST http://localhost:5000/api/users/signup 422 (Unprocessable Entity) 2.chunk.js:377

Source:

 try {
        const response = await fetch(url, {
          method,
          body,
          headers,
          signal: httpAbortCtrl.signal
        });

Source Error Message:

Failed to load resource: the server responded with a status of 422 (Unprocessable Entity)

Source File http-hook.js:

import { useState, useCallback, useRef, useEffect } from 'react';

export const useHttpClient = () => {
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState();

  const activeHttpRequests = useRef([]);

  const sendRequest = useCallback(
    async (url, method = 'GET', body = null, headers = {}) => {
      setIsLoading(true);
      const httpAbortCtrl = new AbortController();
      activeHttpRequests.current.push(httpAbortCtrl);

      try {
        const response = await fetch(url, {
          method,
          body,
          headers,
          signal: httpAbortCtrl.signal
        });

        const responseData = await response.json();

        activeHttpRequests.current = activeHttpRequests.current.filter(
          reqCtrl => reqCtrl !== httpAbortCtrl
        );

        if (!response.ok) {
          throw new Error(responseData.message);
        }

        setIsLoading(false);
        return responseData;
      } catch (err) {
        setError(err.message);
        setIsLoading(false);
        throw err;
      }
    },
    []
  );

  const clearError = () => {
    setError(null);
  };

  useEffect(() => {
    return () => {
      // eslint-disable-next-line react-hooks/exhaustive-deps
      activeHttpRequests.current.forEach(abortCtrl => abortCtrl.abort());
    };
  }, []);

  return { isLoading, error, sendRequest, clearError };
};

responseData usage in register.js file:

    const authSubmitHandler = async event => {
        event.preventDefault();
             try {
                 const formData = new FormData();
                 formData.append('firstname', formState.inputs.firstname.value);
                 formData.append('lastname', formState.inputs.lastname.value);
                 formData.append('email', formState.inputs.email.value);
                 formData.append('password', formState.inputs.password.value);
                 formData.append('license', formState.inputs.license.value);
                 const responseData = await sendRequest(
                    'http://localhost:5000/api/users/signup', 
                    'POST', 
                    formData
                 );

                 auth.login(responseData.userId, responseData.token);
             } catch (err) {}
    };

Any ideas how to fix this…