async_handlers don't work as expected (stop working fine after first async request) (IDFGH-16734)

[mattcarter11]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

General issue report

General issue report

• IDF version → v5.5.1
• SoC → ESP32-D0WD (revision v1.1) or ESP32-S3
• OS → Windows
• Build and flash → With the VSCode esp-idf extension
• Power Supply → USB

What is the expected behavior?

To be able to do the same async request more than once

What is the actual behavior?

1. The first async response works fine
2. The consequent async responses don't work

Steps to reproduce.

1. Clone the async_handler example
2. Simplify the async for simple testing

static esp_err_t long_async(httpd_req_t* req) {
    ESP_LOGI(TAG, "Request URI: %s", req->uri);

    esp_err_t err = httpd_resp_sendstr_chunk(req, "test");
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to send string chunk: %s", esp_err_to_name(err));
        return err;
    }

    err = httpd_resp_sendstr_chunk(req, NULL);
    if (err != ESP_OK) {
        ESP_LOGE(TAG, "Failed to send string chunk: %s", esp_err_to_name(err));
        return err;
    }

    return ESP_OK;
}

3. Build and flash
4. Try curl http://<ip>/long for time.
   • The first time you get a respone
   • The second you don't
   • The third you do and in the logs it seems to log both 2n and 3r
   • The forth gets again stuck
5. Now restart and try curl http://<ip>/long then curl http://<ip>/quick
   • Quick gets stuck

Note

Adding httpd_resp_set_hdr(req, "Connection", "close"); seems to fix the problem partially. I found that in my API, if I also don't read the entire body of the POST/PUT request, they get stuck. I'll try replicating in a simple example

Update 1: the POST/PUT problem seems to happen on Windows with chrome/edge. On chrome Android the problem doesn't seem present

[Ashish285]

Hi @mattcarter11 , thanks for creating this issue!

Can you please try cherry picking this commit cfc0560 and see if this fixes your issue.

[mattcarter11]

How do I cherry-pick if I've installed via the VSCode extension?

P.D: I've added an update about the POST/PUT problem

[Ashish285]

Hi @mattcarter11,

If you followed these instructions to setup the VSCode extension: https://docs.espressif.com/projects/vscode-esp-idf-extension/en/latest/installation.html, then you would have selected ESP-IDF Path. You can go to that path and do a git cherry-pick

[mattcarter11]

@Ashish285 I've tested the tag 6.1, which has the commit in it. But it seems to not fix the problem

[Ashish285]

Hi @mattcarter11 , thanks for coming back on this. I tested running the async handler on ESP32S3 with v6.1-dev and I am unable to reproduce the issue.

for i in {1..5}; do
  ts=$(date '+%Y-%m-%d %H:%M:%S')
  echo -n "[$ts] "
  curl -s http://10.10.2.171/long
done
[2025-11-25 10:45:23] test
[2025-11-25 10:45:23] test
[2025-11-25 10:45:23] test
[2025-11-25 10:45:23] test
[2025-11-25 10:45:23] test

Can you please check once again that you are on the correct commit and test again? Thanks!