CAUTION: SLIPPERY FLOORThe Arduino Library Manager installs the ArduinoJson version 6 by default.
However, using version 5 is highly recommended because version 6 is still in beta stage.
Open the Arduino Library Manager and make sure that ArduinoJson version 5 is installed.
There is currently a bug in the Arduino Core for ESP32 causing the following error:
error: redefinition of 'struct ArduinoJson::Internals::StringFuncs<const char*>'
The solution is to disable
PROGMEM support in ArduinoJson.
To do that, just add the following line at the top of your program:
#define ARDUINOJSON_ENABLE_PROGMEM 0
Then, you may have the following linker error undefined reference to