Troubleshooting

Problems resetting the board

After flashing the firmware via serial do a hard reset of the device (unplug & plug).
There is an issue with the ESP.reset() method. Check https://github.com/esp8266/Arduino/issues/1017 for more info.

Undefined reference to `__ieee754_sqrt'

FIX: You are using an old ESP8266 Core for Arduino

/home/odroid/.platformio/packages/toolchain-xtensa/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/lib/libm.a(lib_a-w_sqrt.o):(.literal+0x8): undefined reference to `__ieee754_sqrt'
/home/odroid/.platformio/packages/toolchain-xtensa/bin/../lib/gcc/xtensa-lx106-elf/4.8.2/../../../../xtensa-lx106-elf/lib/libm.a(lib_a-w_sqrt.o): In function `sqrt':
/home/pi/xtensa/esp-open-sdk/crosstool-NG/.build/src/newlib-2.0.0/newlib/libm/math/w_sqrt.c:69: undefined reference to `__ieee754_sqrt'
collect2: error: ld returned 1 exit status
*** [.pioenvs/sonoff-pow-debug/firmware.elf] Error 1

This is due to a missing function in a core library (https://github.com/esp8266/Arduino/issues/612, not related to ESPurna). It will be probably solved with 2.4.0 version of ESP8266 Core for Arduino. In the meantime a quick fix is to replace the "(...toolchain-xtensa...)/xtensa-lx106-elf/sysroot/lib/libm.a" with the file one: https://files.gitter.im/esp8266/Arduino/Abqa/libm.a.tbz.

Wifi Stops

• First check you supply enough voltage to ESP8266. Not all power supplies are the same.

Unable to login to Web UI

• Use Chrome or Firefox browser.
• Safari and Edge may not work with the WebSockets Auth scheme Espurna uses by default
• Safari has a known issue requesting authentication twice: https://github.com/xoseperez/espurna/pull/1843#issuecomment-523435455

Unstable WiFi when using OpenWrt & mwlwifi

• Known issue with devices using mwlwifi (Linksys WRT32X, linksys 3200acm etc.): https://github.com/kaloz/mwlwifi/issues/278
  https://gitter.im/tinkerman-cat/espurna?at=5d961ada464b432fc1b2a4dd
  https://gitter.im/tinkerman-cat/espurna?at=5da87e7f65dd8569a0f30dd8
• Turning off WMM mode resolves the issue, switching WiFi to 802.11G mode

Custom build unstable when using specific router models

• Known issue with some older router models: https://github.com/xoseperez/espurna/issues/2104#issuecomment-574249525
• Adding -DPIO_FRAMEWORK_ARDUINO_ESPRESSIF_SDK221 to PlatformIO build_flags = ... will may solve the issue
• Arduino IDE provides a menu option for SDK version selection

Release build telnet / websocket on softAP closes after connecting to configured network

• After wifi.reset command or Reconnect button is pressed, TCP connection will be aborted from the client side but neither web server or telnet server will register that event. Any new telnet client will be rejected. Web server will create a second session, possibly causing a crash due to the extensive RAM usage.
• Known issue with Core 2.3.0. Device will eventually reset the connection, but only after ~10 minutes.
• Custom build using latest Core should not have the issue present.