Error MBEDTLS_ERR_SSL_CONN_EOF on api request with Pico W and display

[jonbhanson]

I am trying to access my test endpoint using a Pico W with a Pimoroni Display Pack 2.0, using the their pimoroni-picow-v1.19.12-micropython.uf2 .

I've been having a lot of trouble getting the error (-29312, 'MBEDTLS_ERR_SSL_CONN_EOF'), so I've trimmed my code down to the basics to try to get to the bottom of the trouble. Here's my basic code:

import time
import network
import urequests
import gc
import micropython

from pimoroni import RGBLED
from picographics import PicoGraphics, DISPLAY_PICO_DISPLAY_2,

# set up the hardware
display = PicoGraphics(display=DISPLAY_PICO_DISPLAY_2, rotate=0)

print("starting...")
def network_connect():

    # Set your wifi ssid and password here
    WIFI_SSID = const('wifi')
    WIFI_PASSWORD = const('')

    # Start connection
    wlan = network.WLAN(network.STA_IF)
    wlan.active(True)
    wlan.connect(WIFI_SSID, WIFI_PASSWORD)

    # Wait for connect success or failure
    max_wait = 20
    while max_wait > 0:
        if wlan.status() < 0 or wlan.status() >= 3:
            break
        max_wait -= 1
        print('waiting for connection...')
        time.sleep(1)

    # Handle connection error
    if wlan.status() != 3:
        raise RuntimeError('wifi connection failed %d' % wlan.status())
    else:
        print('connected')
        status = wlan.ifconfig()
        print( 'ip = ' + status[0] )
network_connect()

def poll_server():
    try:
        r = urequests.get("https://us-central1-boiler-monitor-c6c14.cloudfunctions.net/helloWorld")
        print (r.text)
    except Exception as e:
        print(e) 

while True:
    print ("=============")
    print(micropython.mem_info())
    poll_server()
    time.sleep(5)

When I run this, here's the output:

starting...
connected
ip = 10.0.0.78
=============
stack: 548 out of 7936
GC: total: 166016, used: 85616, free: 80400
 No. of 1-blocks: 132, 2-blocks: 30, max blk sz: 4800, max free sz: 5022
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 90736, free: 75280
 No. of 1-blocks: 228, 2-blocks: 42, max blk sz: 4800, max free sz: 1740
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 95856, free: 70160
 No. of 1-blocks: 324, 2-blocks: 54, max blk sz: 4800, max free sz: 1598
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 100976, free: 65040
 No. of 1-blocks: 420, 2-blocks: 66, max blk sz: 4800, max free sz: 1598
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 106096, free: 59920
 No. of 1-blocks: 516, 2-blocks: 78, max blk sz: 4800, max free sz: 1598
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 111216, free: 54800
 No. of 1-blocks: 612, 2-blocks: 90, max blk sz: 4800, max free sz: 1598
None
(-29312, 'MBEDTLS_ERR_SSL_CONN_EOF')
=============
stack: 548 out of 7936
GC: total: 166016, used: 86784, free: 79232
 No. of 1-blocks: 104, 2-blocks: 25, max blk sz: 4800, max free sz: 3985
None
(-29312, 'MBEDTLS_ERR_SSL_CONN_EOF')
=============
stack: 548 out of 7936
GC: total: 166016, used: 89200, free: 76816
 No. of 1-blocks: 120, 2-blocks: 26, max blk sz: 4800, max free sz: 3985
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 94320, free: 71696
 No. of 1-blocks: 216, 2-blocks: 38, max blk sz: 4800, max free sz: 2353
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 99440, free: 66576
 No. of 1-blocks: 312, 2-blocks: 50, max blk sz: 4800, max free sz: 2353
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 104560, free: 61456
 No. of 1-blocks: 408, 2-blocks: 62, max blk sz: 4800, max free sz: 2352
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 109680, free: 56336
 No. of 1-blocks: 504, 2-blocks: 74, max blk sz: 4800, max free sz: 2234
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 114800, free: 51216
 No. of 1-blocks: 600, 2-blocks: 86, max blk sz: 4800, max free sz: 1324
None
(-29312, 'MBEDTLS_ERR_SSL_CONN_EOF')
=============
stack: 548 out of 7936
GC: total: 166016, used: 86784, free: 79232
 No. of 1-blocks: 104, 2-blocks: 25, max blk sz: 4800, max free sz: 3631
None
(-29312, 'MBEDTLS_ERR_SSL_CONN_EOF')
=============
stack: 548 out of 7936
GC: total: 166016, used: 89200, free: 76816
 No. of 1-blocks: 120, 2-blocks: 26, max blk sz: 4800, max free sz: 3631
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 94320, free: 71696
 No. of 1-blocks: 216, 2-blocks: 38, max blk sz: 4800, max free sz: 1997
None
Hello from Firebase!
=============
stack: 548 out of 7936
GC: total: 166016, used: 99440, free: 66576
 No. of 1-blocks: 312, 2-blocks: 50, max blk sz: 4800, max free sz: 1997
None
Hello from Firebase!

I thought the error would be related to memory usage, but if I understand this output correctly (I have zero experience with micropython) the error does not seem related to memory usage.

Any suggestions about what might be causing this error?

[MATTYGILO]

I am having this error also on an esp32s3 it seems to be a firebase problem. Here are some of the other people having the problem
https://forums.raspberrypi.com/viewtopic.php?t=346307(https://forums.raspberrypi.com/viewtopic.php?t=346307](https://forums.raspberrypi.com/viewtopic.php?t=346307)
https://forums.pimoroni.com/t/galactic-unicorn-mbedtls-err-ssl-conn-eof-from-urlopen-at-random/21104

[karfas]

For me, this looks like some rate limiting measure on the API (Firebase) side.
After 5 successful connections, you get a few times MBEDTLS_ERR_SSL_CONN_EOF, then again 5 successful, then ...

[scruss]

adding r.close() near the end of poll_server() will help with your memory usage.

Like karfas, I think this might be a rate limiting issue. If this is a home heating system, querying it every 5 seconds is overkill.

Pimoroni have tweaked stuff in their distribution, too. It may be something caused in their code.

[MATTYGILO]

Please can you double check I am reading the correct section on rate limits

I have found these limits about firebase functions

API calls (CALL)	
16 per 100 seconds

https://firebase.google.com/docs/functions/quotas#rate_limits

This would suggest that on average you should wait 6.25s

[Josverl]

When calling any api, it makes sense to code not only for the happy path.
Http APIs generally use return code 200-299 for valid responses, everything else signals something is off.
Firebase returns 500 for rate limiting (industry standard would be 429)
Checking for either 200 or 500 would help your code deal with the APIs responses better.

https://en.m.wikipedia.org/wiki/List_of_HTTP_status_codes