I have an ESP32-C3-OLED board which works well when I do
OLED tuff (writing to the LCD screen)
WIFI (got IP address)
sensor with BME280
But when I add either ArduinoOTA or WebServer, it crashes. (stacktrace below)
#include <WebServer.h>
WebServer wserver(80);
void doweb() {
Serial.println("WEB");
}
void setup() {
Serial.begin(115200);
Serial.print(heap_caps_get_free_size(MALLOC_CAP_8BIT));
wserver.on("/", doweb);
wserver.onNotFound(doweb);
wserver.begin();
}
static int c;
static int uptime;
void loop() {
delay(1000);
if (c++ > 50) {
c = 0;
Serial.print("ALive");
Serial.println(uptime++);
}
}
If I comment wserver.begin() it works.
Any help will be apreciated
17:23:57.771 -> assert failed: xQueueSemaphoreTake queue.c:1709 (( pxQueue ))
It looks like nothing in your sketch is actually wrong. From what I’ve seen, the ESP32-C3 is a bit unstable when you use the classic WebServer class (and sometimes ArduinoOTA).
assert failed: xQueueSemaphoreTake queue.c:1709
usually comes from inside the ESP32 core itself, not from user code.
I’m not 100% sure, but it seems to be a known issue specifically on the C3 boards, especially the OLED versions. The older WebServer implementation wasn’t really designed for the RISC-V C3.
You might want to try switching to ESPAsyncWebServer or the ESP-IDF esp_http_server those tend to be a lot more stable on the C3. Also updating to the latest ESP32 Arduino core sometimes helps.
So my guess is: your code is fine, it’s more likely a C3 WebServer bug.
Thanks for your reply. But Arduino OTA also lead to crash.
I use the latest esp32 libraries 3.3.3
Thanks for the details.
Try disabling the OLED, turning off WiFi sleep, or using core 2.0.14 many people report it’s much more stable there.
sonofcy
November 26, 2025, 1:34am
5
Try backing off the BOARDS espressif from 3.x to 2.0.17
Your topic does not indicate a problem with IDE 2.x and therefore has been moved to a more suitable category of the forum.
With esp32 2.0.x, it fail to use the serial so unusable.
If 2.0.x breaks serial for you, it might not be the core itself but the USB-CDC setting or the board variant definition. On some ESP32 boards the 2.0.x series defaults to USB-CDC-on-boot, and that can make the normal UART appear dead. I’m not completely sure, but disabling USB-CDC in menuconfig or switching the upload/monitor port back to the classic UART usually restores serial.
So 2.0.17 can still work, but only if the serial mode is configured correctly.
noiasca
November 26, 2025, 11:09am
9
can you try with one of the examples which came with the platform package?
sonofcy
November 26, 2025, 1:05pm
10
Since it does work for many others, more info is needed. Start with the built in examples then try backing off the boards to 2.0.1x as suggested in several posts to you.
With 2.0.17 I got:
17:47:39.956 -> assert failed: tcpip_send_msg_wait_sem IDF/components/lwip/lwip/src/api/tcpip.c:455 (Invalid mbox)
It seems that wifi need to be started before configuring anything network related.
Thanks for your hints and help. It works now