If you are trying to implement OTA functionality for your ESP32 / ESP8266 with AP Wifi Mode enabled, try this simple Arduino Library:

Library link: Github Repository

You can also install the library directly from Arduino IDE. Just click on Library Manager and search for ESP2SOTA

By installing the library, two code samples will be available, one for AP Mode and the other one for Client Mode

Sample sketch:

#include <WiFi.h>
#include <WiFiAP.h>
#include <WebServer.h>
/* INCLUDE ESP2SOTA LIBRARY */
#include <ESP2SOTA.h>

const char* ssid = "ESP2SOTA";
const char* password = "123456789abc";

WebServer server(80);

void setup(void) {
  Serial.begin(115200);
  WiFi.mode(WIFI_AP);  
  WiFi.softAP(ssid, password);
  delay(1000);
  IPAddress IP = IPAddress (10, 10, 10, 1);
  IPAddress NMask = IPAddress (255, 255, 255, 0);
  WiFi.softAPConfig(IP, IP, NMask);
  IPAddress myIP = WiFi.softAPIP();
  Serial.print("AP IP address: ");
  Serial.println(myIP);

  /* SETUP YOR WEB OWN ENTRY POINTS */
  server.on("/myurl", HTTP_GET, []() {
    server.sendHeader("Connection", "close");
    server.send(200, "text/plain", "Hello there!");
  });

  /* INITIALIZE ESP2SOTA LIBRARY */
  ESP2SOTA.begin(&server);
  server.begin();
}

void loop(void) {
  /* HANDLE UPDATE REQUESTS */
  server.handleClient();

  /* YOUR LOOP CODE HERE */


  
  delay(5);
}