esp-idf: Intermittent http server error: httpd_txrx: httpd_sock_err: error in recv : 104 (IDFGH-5593)

Environment

• Development Kit: ESP32-PICO-Kit
• Kit version (for WroverKit/PicoKit/DevKitC): v4.1
• Module or chip used: ESP32-PICO-D4
• IDF version (run git describe --tags to find it): 4.3
• Build System: idf.py
• Compiler version (run xtensa-esp32-elf-gcc --version to find it): 8.4.0
• Operating System: WIndows 10
• (Windows only) environment type: PowerShell
• Using an IDE?: Yes (Eclipse)
• Power Supply: USB

Problem Description

I am running an application on my ESP32 Pico kit which runs an http REST server which also serves files. I have a number of request handlers for REST paths, and I have one handler for a built-in web page which is modeled after the example code provided by Espressif for a REST server. It serves web pages from a spiffs partition.

I run the server continually and have the monitor on. Approximately once per day I will get a couple of messages on the monitor as follows:

W (923632) httpd_txrx: httpd_sock_err: error in recv : 104
W (923642) httpd_txrx: httpd_sock_err: error in recv : 104

These will occur even though my server is IDLE: I have no requests for web pages or REST commands being sent. The application otherwise appears to be working normally, and I have not noticed an error in behavior other than to see these warnings appear. If fact, if I execute a wide variety of REST API calls and make requests to the web server, I do not get these messages. They seem to appear independent of my use of the server.

I’ve done quite a bit of research on the 104 (connection reset by peer) error but have not been able to come to a conclusion on what the cause could be, especially since they occur when I am not making any requests to the server.

Expected Behavior

During operation of http server application, I should not see 104 (connection reset by peer) errors

Actual Behavior

During operation of http server application, I occasionally see 104 (connection reset by peer) errors, even if I am not making any requests to the server

Steps to reproduce

1. Start application with console monitor connected and on
2. Start http server and verify correct initialization and operation of the REST API and http server without errors or warnings
3. Stop sending commands/requests to the server and let it run idle for up to 1 day
4. Observe 104 error appear on the monitor

Code to reproduce this issue

// the code should be wrapped in the ```cpp tag so that it will be displayed better.
#include "esp_log.h"

void app_main()
{

}

// If your code is longer than 30 lines, GIST is preferred.

Debug Logs

Here’s the monitor output beginning with boot-up

entry 0x40080678
I (27) boot: ESP-IDF v4.3-dirty 2nd stage bootloader
I (27) boot: compile time 17:53:18
I (27) boot: chip revision: 1
I (31) boot_comm: chip revision: 1, min. bootloader chip revision: 0
I (38) boot.esp32: SPI Speed      : 40MHz
I (42) boot.esp32: SPI Mode       : DIO
I (47) boot.esp32: SPI Flash Size : 4MB
I (51) boot: Enabling RNG early entropy source...
I (57) boot: Partition Table:
I (60) boot: ## Label            Usage          Type ST Offset   Length
I (68) boot:  0 nvs              WiFi data        01 02 00009000 00006000
I (75) boot:  1 phy_init         RF data          01 01 0000f000 00001000
I (83) boot:  2 factory          factory app      00 00 00010000 00100000
I (90) boot:  3 www              Unknown data     01 82 00110000 00032000
I (97) boot: End of partition table
I (102) boot_comm: chip revision: 1, min. application chip revision: 0
I (109) esp_image: segment 0: paddr=00010020 vaddr=3f400020 size=1fb84h (129924) map
I (166) esp_image: segment 1: paddr=0002fbac vaddr=3ffb0000 size=0046ch (  1132) load
I (167) esp_image: segment 2: paddr=00030020 vaddr=400d0020 size=a1c30h (662576) map
I (422) esp_image: segment 3: paddr=000d1c58 vaddr=3ffb046c size=0409ch ( 16540) load
I (429) esp_image: segment 4: paddr=000d5cfc vaddr=40080000 size=16f4ch ( 94028) load
I (469) esp_image: segment 5: paddr=000ecc50 vaddr=50000000 size=00010h (    16) load
I (482) boot: Loaded app from partition at offset 0x10000
I (482) boot: Disabling RNG early entropy source...
I (494) cpu_start: Pro cpu up.
I (494) cpu_start: Starting app cpu, entry point is 0x40081498
0x40081498: call_start_cpu1 at C:/Users/mdbra/Documents/esp-idf/components/esp_system/port/cpu_start.c:141

I (0) cpu_start: App cpu up.
I (508) cpu_start: Pro cpu start user code
I (508) cpu_start: cpu freq: 160000000
I (508) cpu_start: Application information:
I (513) cpu_start: Project name:     BD-PTB
I (517) cpu_start: Compile time:     Jul 23 2021 06:00:27
I (524) cpu_start: ELF file SHA256:  ca02407320255093...
I (530) cpu_start: ESP-IDF:          v4.3-dirty
I (535) heap_init: Initializing. RAM available for dynamic allocation:
I (542) heap_init: At 3FFAE6E0 len 00001920 (6 KiB): DRAM
I (548) heap_init: At 3FFB8ED0 len 00027130 (156 KiB): DRAM
I (554) heap_init: At 3FFE0440 len 00003AE0 (14 KiB): D/IRAM
I (561) heap_init: At 3FFE4350 len 0001BCB0 (111 KiB): D/IRAM
I (567) heap_init: At 40096F4C len 000090B4 (36 KiB): IRAM
I (574) spi_flash: detected chip: gd
I (578) spi_flash: flash io: dio
I (583) cpu_start: Starting scheduler on PRO CPU.
I (0) cpu_start: Starting scheduler on APP CPU.
I (592) BD-PTB: Setting up I/O
I (602) BD-PTB: Setting up LEDs
I (1102) BD-PTB: Setting up buttons
I (1102) gpio: GPIO[37]| InputEn: 1| OutputEn: 0| OpenDrain: 0| Pullup: 0| Pulldown: 0| Intr:3
I (1102) gpio: GPIO[38]| InputEn: 1| OutputEn: 0| OpenDrain: 0| Pullup: 0| Pulldown: 0| Intr:3
I (1112) BD-PTB: Configuration
I (1142) BD-PTB: Running SW version 1.2
I (1142) BD-PTB: Configuring points
I (1152) BD-PTB: WifiLink: starting WiFi
I (1172) wifi:wifi driver task: 3ffc62fc, prio:23, stack:6656, core=0
I (1172) system_api: Base MAC address is not set
I (1172) system_api: read default base MAC address from EFUSE
I (1192) wifi:wifi firmware version: c7d0450
I (1192) wifi:wifi certification version: v7.0
I (1192) wifi:config NVS flash: enabled
I (1192) wifi:config nano formating: disabled
I (1192) wifi:Init data frame dynamic rx buffer num: 32
I (1202) wifi:Init management frame dynamic rx buffer num: 32
I (1202) wifi:Init management short buffer num: 32
I (1212) wifi:Init dynamic tx buffer num: 32
I (1212) wifi:Init static rx buffer size: 1600
I (1212) wifi:Init static rx buffer num: 10
I (1222) wifi:Init dynamic rx buffer num: 32
I (1222) wifi_init: rx ba win: 6
I (1232) wifi_init: tcpip mbox: 32
I (1232) wifi_init: udp mbox: 6
I (1232) wifi_init: tcp mbox: 6
I (1242) wifi_init: tcp tx win: 5744
I (1242) wifi_init: tcp rx win: 5744
I (1252) wifi_init: tcp mss: 1440
I (1252) wifi_init: WiFi IRAM OP enabled
I (1252) wifi_init: WiFi RX IRAM OP enabled
I (1262) BD-PTB: WifiLink: Checking for existing Wifi connection
I (1272) phy_init: phy_version 4670,719f9f6,Feb 18 2021,17:07:07
I (1362) wifi:mode : sta (d8:a0:1d:5d:cb:64)
I (1372) wifi:enable tsf
I (1382) wifi:new:<7,0>, old:<1,0>, ap:<255,255>, sta:<7,0>, prof:1
I (1382) wifi:state: init -> auth (b0)
I (1382) wifi:state: auth -> assoc (0)
I (1392) wifi:state: assoc -> run (10)
I (1412) wifi:connected with Antioch, aid = 3, channel 7, BW20, bssid = 20:c9:d0:20:04:e7
I (1412) wifi:security: WPA2-PSK, phy: bgn, rssi: -49
I (1412) wifi:pm start, type: 1

I (1412) wifi:AP's beacon interval = 102400 us, DTIM period = 3
I (1422) BD-PTB: wifiEvent: wifi connected
I (3152) esp_netif_handlers: sta ip: 192.168.1.32, mask: 255.255.255.0, gw: 192.168.1.1
I (3152) BD-PTB: wifiEvent: wifi obtained IP
I (3152) BD-PTB: Wifi connected with prior configuration
I (3162) BD-PTB: SSID = Antioch
I (3162) BD-PTB: MAC address = D8:A0:1D:5D:CB:64
I (3172) BD-PTB: IP address = 192.168.1.32
I (3172) BD-PTB: Gateway = 192.168.1.1
I (3182) BD-PTB: Netmask = 255.255.255.0
I (3182) BD-PTB: Setting up mDNS
I (3192) BD-PTB: mDNS host name = BD-PTB-5DCB64
I (3202) BD-PTB: Starting web server
I (3202) BD-PTB: Starting HTTPD server
I (3222) BD-PTB: Partition /www size: total: 180971, used: 58232
I (3472) BD-PTB: Initialization complete
W (923632) httpd_txrx: httpd_sock_err: error in recv : 104
W (923642) httpd_txrx: httpd_sock_err: error in recv : 104

Other items if possible

sdkconfig.txt