Axios 1.3.4 typescript error for AxiosRequestConfig #5573

Argument of type '(config: InternalAxiosRequestConfig<any>) => AxiosRequestConfig<any>' is not assignable to parameter of type '(value: InternalAxiosRequestConfig<any>) => InternalAxiosRequestConfig<any> | Promise<InternalAxiosRequestConfig<any>>'.
  Type 'AxiosRequestConfig<any>' is not assignable to type 'InternalAxiosRequestConfig<any> | Promise<InternalAxiosRequestConfig<any>>'.
    Type 'AxiosRequestConfig<any>' is not assignable to type 'InternalAxiosRequestConfig<any>'.
      Types of property 'headers' are incompatible.
        Type 'AxiosHeaders | (Partial<RawAxiosHeaders & { Accept: AxiosHeaderValue; "Content-Length": AxiosHeaderValue; "User-Agent": AxiosHeaderValue; "Content-Encoding": AxiosHeaderValue; Authorization: AxiosHeaderValue; } & { ...; }> & Partial<...>) | undefined' is not assignable to type 'AxiosRequestHeaders'.
          Type 'undefined' is not assignable to type 'AxiosRequestHeaders'.
            Type 'undefined' is not assignable to type 'Partial<RawAxiosHeaders & { Accept: AxiosHeaderValue; "Content-Length": AxiosHeaderValue;
To Reproduce
create react sandbox with axios latest version 1.3.4
create basic interceptor (mentioned below)
sample https://codesandbox.io/s/vigilant-elbakyan-wdjzgd?file=/src/interceptor.ts
Code snippet
import




    
 axios, { AxiosRequestConfig, InternalAxiosRequestConfig } from "axios";
export const axiosInstance = axios.create({
  baseURL: SOME_URL
});
// Interceptors
axiosInstance.interceptors.request.use(
  (config): AxiosRequestConfig => {
    return config;
  (error): any => {
    return Promise.reject(error);
axiosInstance.interceptors.response.use(
  async (response): Promise<any> => {
    return response;
  async (error): Promise<any> => {
    return Promise.reject(error);
Expected behavior
AxiosRequestConfig is using following type definition for headers
headers?: (RawAxiosRequestHeaders & MethodsHeaders) | AxiosHeaders;
instead If we use InternalAxiosRequestConfig, mentioned TS error goes away. but since it is called internal, it is confusing for devs to use it or not.
export interface InternalAxiosRequestConfig<D = any> extends AxiosRequestConfig<D> {
  headers: AxiosRequestHeaders;
Axios Version
1.3.4
Adapter Version
No response
Browser
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Browser Version
No response
Node.js Version
No response
No response
Additional Library Versions
No response
Additional context/Screenshots
No response
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