ESP8266WebServer hangs after updating to 2.5.0

[moose4lord]

Basic Infos

• This issue complies with the issue POLICY doc.
• I have read the documentation at readthedocs and the issue is not addressed there.
• I have tested that the issue is present in current master branch (aka latest git).
• I have searched the issue tracker for a similar issue.
• If there is a stack dump, I have decoded it.
• I have filled out all fields below.

Platform

• Hardware: ESP8266
• Core Version: 2.5.0
• Development Env: Arduino IDE
• Operating System: MacOS

Settings in IDE

• Module: NodeMCU1.0
• Flash Mode: n/a
• Flash Size: 4MB/3MB
• lwip Variant: v2 Lower Memory
• Reset Method: n/a
• Flash Frequency: n/a
• CPU Frequency: 80Mhz
• Upload Using: SERIAL
• Upload Speed: 115200

Problem Description

After updating to v2.5.0 my sketch can't get a reliable connection to the ESP8266WebServer server. Trying to connect to the ESP from a browser succeeds occasionally, but most of the time the browser hangs and eventually gives up.

I loaded the simple HelloServer example sketch that comes with ESP8266WebServer and it does the same thing. The browser just sits there. Tried various lwIP variants, but none helped. Oddly, turning on all debug options made the problem happen less often.

It seems related to issue #5725, although for me ping requests constantly timeout.

Revert back to v2.4.2 and the problem goes away.

MCVE Sketch

Use the HelloServer example sketch provided with ESP8266WebServer.

Debug Messages

Problem goes away (or at least gets much better) when all debug options are enabled.

[moose4lord]

Another clue, if I comment out the MDNS.begin("esp8266") and the MDNS.update() statements in the HelloServer sketch, the problem goes away. Here's the sketch:

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <ESP8266WebServer.h>
#include <ESP8266mDNS.h>

#ifndef STASSID
#define STASSID "your-ssid"
#define STAPSK  "your-password"
#endif

const char* ssid = STASSID;
const char* password = STAPSK;

ESP8266WebServer server(80);

const int led = 13;

void handleRoot() {
  digitalWrite(led, 1);
  server.send(200, "text/plain", "hello from esp8266!");
  digitalWrite(led, 0);
}

void handleNotFound() {
  digitalWrite(led, 1);
  String message = "File Not Found\n\n";
  message += "URI: ";
  message += server.uri();
  message += "\nMethod: ";
  message += (server.method() == HTTP_GET) ? "GET" : "POST";
  message += "\nArguments: ";
  message += server.args();
  message += "\n";
  for (uint8_t i = 0; i < server.args(); i++) {
    message += " " + server.argName(i) + ": " + server.arg(i) + "\n";
  }
  server.send(404, "text/plain", message);
  digitalWrite(led, 0);
}

void setup(void) {
  pinMode(led, OUTPUT);
  digitalWrite(led, 0);
  Serial.begin(115200);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  if (MDNS.begin("esp8266")) {
    Serial.println("MDNS responder started");
  }

  server.on("/", handleRoot);

  server.on("/inline", []() {
    server.send(200, "text/plain", "this works as well");
  });

  server.onNotFound(handleNotFound);

  server.begin();
  Serial.println("HTTP server started");
}

void loop(void) {
  server.handleClient();
  MDNS.update();
}

Can someone try this out on their hardware/network? I'd like to know if the problem is reproducible elsewhere, or some kind of quirk with my hardware/network. Although, everything works fine with v2.4.2, so I don't think it's something I did.

[d-a-v]

Have you tried to "erase flash" in tools menu ?

[moose4lord]

Yes, I've tried the "Erase Flash: All Flash Contents" option. No change.

[d-a-v]

Reproduced in master with HelloServer example.
@LaborEtArs @hreintke initializing m_GotIPHandler and m_DisconnectedHandler in MDNS.begin() breaks something. Everything is fine including mDNS resolution when these initializations are commented.

[moose4lord]

Thanks @d-a-v. I'm relieved I wasn't doing something dumb. :)

[hreintke]

@d-a-v : test results on mdns gitter, please take a look.

[LaborEtArs]

@moose4lord @d-a-v: Is one of the registered event callbacks ever called?

[TD-er]

OK, also good to know I'm not loosing my mind too :)
It seems to be related to some change made in the last month (or maybe even less, haven't had much time for my projects last weeks)
In the latest builds I have running here the webserver crashes the node on several specific pages (ofcourse one of the pages related to something I was working on) and when I went back to a build of around Jan 10, it was working fine.

[moose4lord]

@LaborEtArs initially the requests from the browser are accepted by the ESP, the callback is called and runs successfully, but the response back to the browser is very delayed. But if I keep hitting refresh in the browser, the ESP eventually gets overwhelmed, the callbacks don't get called, and the ESP stops responding all together. Sometimes it will recover and start working again, but only for a short time.

It seems to get better if I add a small delay(10) in the callback. If I set the debug level to log everything, it seems to get better too.

Sorry I can't be more specific. It's a pretty erratic fail.

[d-a-v]

I have news, long story short:

• I have an ESP module on which HelloServer.ino works (LEAmDNS responding, webserver responding)
• I have another one on which it doesn't work with the following symptoms:
  (at least CORE debug option needs to be enabled)

IP address: 10.0.1.154
MDNS responder started
HTTP server started
bcn_timout,ap_probe_send_start
ap_probe_send over, rest wifi status to disassoc
state: 5 -> 0 (1)
rm 0
IP address: 10.0.1.154
MDNS responder started
HTTP server started
bcn_timout,ap_probe_send_start
ap_probe_send over, rest wifi status to disassoc
state: 5 -> 0 (1)
rm 0
...

However, webserver works and no more disconnection when I comment MDNS.update() from loop().
It doesn't mean LEA mDNS does not work (because it works with another esp).

In every case I used Generic board, DOUT, 4MB (both are) and the same binary flashed onto both of them, used esptool.py, erase flash, flash with verify, and watch it run on serial console. I also tried with an external power supply.

edit:

---

update: Issue disappears by using previous nonos-sdk FW (SDK:2.2.1(cfd48f3))

---

update2: to test: (this will keep 2.5.0/master core sources, only FW is downgraded)

git remote add dav https://github.com/d-a-v/Arduino.git
git fetch dav
git checkout --track dav/fwregress

back to master:

git checkout master

---

[TD-er]

Could it be somehow related to the issues seen when the wifi gets disconnected, but the open sockets are not closed because the disconnect is not (always) being noticed outside the core libraries?

The crashes I've seen were due to Exception 28 issues, that's why I was looking into my own code first.

[d-a-v]

Could it be somehow related to the issues seen when the wifi gets disconnected, but the open sockets are not closed because the disconnect is not (always) being noticed outside the core libraries?

#5703 is merged and included in 2.5.0.

In this issue, WiFi is not supposed to go off, and there's no freeze, reboot, or error. Just WiFi loosing its connection and trying to reconnect, and not on all boards.