Cannot initialize ESP-AT Lib

Summary: Getting error “Cannot initialize ESP-AT Lib!” when using Wifi HTTP or HTTPS examples from the Wiki at . An older version of the ESP-AT Library works but the current version on Github doesn’t.


I’ve been using the WIO Terminal with Wifi for some time and it always connects to the network and to the webserver just fine.

But today I installed Arduino on a different computer and downloaded all the libraries I needed from Github. Now when I run the WIFI example I get the error “Cannot initialize ESP-AT Lib”.

If I use a previous release of the ESP-AT Library it works fine. But the current release on Github doesn’t.

I would have posted this in the “issues” section on Github but it looks like it has been disabled.

Hi @Dennis_Mabrey

I just tested with the latest esp-at lib and seems to be working fine on my end

Which verison of esp-at lib you are using, let me recreate this

Hi. I have the same problem using the develop branch of the library. The WiFiScan example works (as you have shown here) but anything that actually connects to a network (e.g. SimpleWiFiServer) fails with the following sort of output in the serial monitor (I haven’t managed to find a version of the esp-at library that works for me):

09:41:41.739 -> Device reset detected!
09:41:45.414 -> Cannot initialize ESP-AT Lib!
09:41:52.539 -> [E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4
09:41:52.539 -> 
09:41:53.044 -> Connecting to WiFi..
09:41:53.525 -> Connecting to WiFi..
09:41:54.035 -> Connecting to WiFi..
09:41:54.510 -> Connecting to WiFi..
09:41:55.017 -> Connecting to WiFi..
09:41:55.525 -> Connecting to WiFi..
09:41:56.027 -> Connecting to WiFi..
09:41:56.507 -> Connecting to WiFi..
09:41:57.016 -> Connecting to WiFi..
09:41:57.531 -> Connecting to WiFi..
09:41:58.010 -> Connecting to WiFi..
09:41:58.514 -> Connecting to WiFi..
09:41:59.017 -> Connecting to WiFi..
09:41:59.523 -> Connecting to WiFi..
09:42:00.030 -> Connecting to WiFi..
09:42:00.501 -> Connecting to WiFi..
09:42:00.838 -> [E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4
09:42:00.838 -> 
09:42:01.008 -> Connecting to WiFi..
09:42:01.515 -> Connecting to WiFi..
09:42:02.021 -> Connecting to WiFi..
09:42:02.021 -> Connected to the WiFi network
09:42:02.021 -> IP Address: [E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4
09:42:02.595 -> 
09:42:03.821 ->

This was generated by this sketch:

#include "AtWiFi.h"
const char* ssid = "xxxx";
const char* password =  "xxxx";
void setup() {
    while(!Serial); // Wait for Serial to be ready
    // Set WiFi to station mode and disconnect from an AP if it was previously connected
    WiFi.begin(ssid, password);
    while (WiFi.status() != WL_CONNECTED) {
        Serial.println("Connecting to WiFi..");
    Serial.println("Connected to the WiFi network");
    Serial.print("IP Address: ");
    Serial.println (WiFi.localIP()); // prints out the device's IP address
void loop() {

I was using the developer release from here It was from commit 1bf13e4.

All the libraries I used were from the links from the wiki network page form here

I used this library before and it just recently started having this problem. As a temporary solution try downloading from the last May 08,2020 commit. It should work ok as a temp solution.

So I rolled back esp-at to 8th May and that caused errors in atUnified and atWiFi. So I rolled those back to 8th May as well and finally it worked. Thanks @Dennis_Mabrey for the pointer in the right direction - I’m very pleased my brand new Wio Terminal can now connect to wifi.

16:40:41.143 -> Connecting to WiFi..
16:40:41.650 -> Connecting to WiFi..
16:40:42.158 -> Connecting to WiFi..
16:40:42.669 -> Connecting to WiFi..
16:40:42.669 -> Connected to the WiFi network
16:40:42.669 -> IP Address:

Huh that’s funny I had not rolled those back and they worked for me. Anyway glad it is working for you now. Hopefully they will resolve the esp-at library problem…

Hi. It look like I am having this issue.

Do you know if there is a specific fix for this…

I have followed the instructions as per

I copied the Scanning Wi-Fi Network Example Code and this is the serial monitor:-

Device reset sequence finished!
Cannot initialize ESP-AT Lib!
[E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4

[E][WiFiGeneric.cpp:477] mode(): Could not set mode! -1
[E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4

Setup done
scan start
[E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4

[E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4

[E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4

[E][WiFiGeneric.cpp:477] mode(): Could not set mode! -1
scan done
-2 networks found

scan start
scan done
-1 networks found

Arduino libraries:


Had WIO Terminal for a Week… Looks really good :slight_smile:

I think you didn’t upgrade the wifi firmware

Hello, I’m having same issue.

Device reset sequence finished!
Cannot initialize ESP-AT Lib!

I follow both procedures to upgrade firmware (UF2 and ambd_flash_tool.py2) but firmware upgrade does not work…

Using the UF2 procedure show in screen the message " Burn RTL8720 fw" but don’t finish (at least I can’t see any message indicating that).

Using the procedure it returns:

Do you have any suggest.

try it with the win powershell… worked for me

Thanks Borroz. I tryed and same result .


Take note, after erase allways receive Error! and you receive done!!

@pacocuervo you need to enter the UART Download mode before flashing . to enter the UART Download mode . you need to sliding the power switch twice quickly . For more reference, please also see here.

Many thanks… after many many tryes I got succes on programming firmware!!! really I don’t know what was the condition but from now I can update the firmware and if I repeat the procedure, no problem. I can update the firmware without problem…

But now If I program with the next skecth:

#include “AtWiFi.h”

void setup() {

// Set WiFi to station mode and disconnect from an AP if it was previously connected

Serial.println("Setup done");


… I continue having same result.

Device reset sequence finished!
Cannot initialize ESP-AT Lib!
[E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4

[E][WiFiGeneric.cpp:477] mode(): Could not set mode! -1
[E][esp_event_loop.c:99] at_unified_cb(): at_unified evt: 4

Really, I’m very angry. :frowning_face: I was thinking to use wio in my projects (first purchase to start testing) and as I can see is not very reliable.

no need to get VERY angry :sunglasses:

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