ESP32 websocket client misses first received message

[biterror]

I am using the ESP32 websocket client (idf version v4.2-dev-701-g0ae960f2f-dirty) to connect to a linux box running a libwebsocket server. The server side sends out a JSON formatted message immediately after a new client connects. Other clients are receiving this message just fine, but the ESP32 ws client seems to miss the first message most of the time.

If I add a delay of 100 ms to the server (between connect and the message transmission), ESP32 gets the message most of the time. With a 250 ms delay, ESP32 gets 99.8% of the messages.

Is this a known bug in the ws client implementation? Does a fix exist?

EDIT: I updated to idf version v4.2-dev-1266-g2dc4bfe78-dirty, but the problem remains the same.

Thanks!

[Haresh Prajapati]

Did you find any solution?
I am also facing same problem.

[biterror]

I believe the bug was not in lws but in Ethernet code and I think it has been fixed a long time ago. I'm not seeing any problems with Ethernet (running idf 4.4.6), but I'm not using lws in my current projects.

Which idf version are you using?

[Haresh Prajapati]

I believe the bug was not in lws but in Ethernet code and I think it has been fixed a long time ago. I'm not seeing any problems with Ethernet (running idf 4.4.6), but I'm not using lws in my current projects.

Which idf version are you using?

I am using idf 5.0.0

Whenever a websocket is connected to a server, the server sends some JSON data with the connection, but on esp side, I didn't get that.

I tried to `esp_websocket_client_start` and `esp_websocket_client_stop` websocket_client until I didn't receive that data.
but it is working after several tries (sometime works on two try, some time 10 or above and some time takes 10 minutes or more)

[locustcox]

Issue still exists. My current workaround is to add a delay on my Python server before sending any messages since the first message gets dropped on the ESP32.

[rsaxvc]

One case seems to be if the server responds over HTTP during the protocol change: https://github.com/espressif/esp-protocols/issues/396

If you have control of the server, you may try to delay sending to the client until the protocol change to websocket is completed.