Hardware:

Board: DOIT ESP32 DEVKIT V1
Core Installation version: 1.0.4
IDE name: Platform.io
Flash Frequency: Can't tell (Crystal is 40MHz?)
PSRAM enabled: Can't tell
Upload Speed: 921600
Computer OS: Mac OSX

Description:

After reading the http response line with WiFiClient::readBytesUntil() calling WiFiClient::flush() hangs indefinitely. Doesn't always happen, best guess is it depends on response length. First noticed with 204 No Content response from an influxdb server.

Sketch:

#include <WiFi.h> #include <WiFiClient.h> const char ssid[] = "FIXME"; const char pass[] = "FIXME"; void setup() { Serial.begin(115200); WiFiClient client; WiFi.begin(ssid, pass); WiFi.waitForConnectResult(); client.connect("httpbin.org", 80); client.printf("GET /status/200 HTTP/1.0\r\nHost: httpbin.org\r\n\r\n"); auto res = client.readStringUntil('\n'); Serial.println(res); client.flush(); Serial.println("Done."); } void loop() { }

Debug Messages:

[D][WiFiGeneric.cpp:337] _eventCallback(): Event: 0 - WIFI_READY [D][WiFiGeneric.cpp:337] _eventCallback(): Event: 2 - STA_START [D][WiFiGeneric.cpp:337] _eventCallback(): Event: 4 - STA_CONNECTED [D][WiFiGeneric.cpp:337] _eventCallback(): Event: 7 - STA_GOT_IP [D][WiFiGeneric.cpp:381] _eventCallback(): STA IP: 192.168.1.2, MASK: 255.255.255.0, GW: 192.168.1.1 HTTP/1.1 204 NO CONTENT