Socket is not connected

[OleksandrGora]

Dear all.
Sometimes I get the error: [WiFiClient.cpp:517] flush(): fail on fd 50, errno: 128, "Socket is not connected".
The program does not freeze. I did not find any suggestions in Q&A section.
Where to dig?

[mobizt]

That's a bug in ESP32 WiFiClient that cannot detect the server disconnection when TCP session was kept alive when using with other SSL clients or ESP_SSLClient.

With ESP_SSLClient, you should set session timeout like this.

FirebaseClient/examples/RealtimeDatabase/Async/Callback/StreamConcurentcy/StreamConcurentcy.ino

Line 120 in f700d7e

ssl_client1.setSessionTimeout(150);

[mobizt]

The timeout value set above is the seconds.

[OleksandrGora]

Thank you @mobizt.
I will try. Closing at the moment the discussion.