mDash gives error on OTA

I want to update my Arduino Uno code wirelesslly. I am following this tutorial:

The firmware URL (https://mdash.net/downloads/ccm/ccm.esp8266.zip)
mentioned on above video is no longer available.

So, I flashed my esp8266 with this firmware successfully:
https://github.com/mongoose-os-apps/demo-c/releases/download/latest/demo-c-esp8266.zip

I connected my esp8266 with Arduino uno with following wire connections:

ESP 8266 3.3V to Arduino 3.3V
ESP 8266 GND to Arduino GND
ESP 8266 D1 to Arduino RESET
ESP 8266 D6 to Arduino pin 11
ESP 8266 D7 to Arduino pin 12
ESP 8266 D5 to Arduino pin 13
ESP 8266 TX to Arduino RX
ESP 8266 RX to Arduino TX

After that I connected arduino to the laptop via USB. And on mdash.net the device shows online. Now on Arduino IDE I exported compiled binary of testing code into a .hex file which then I upload to mdash.net
But it gives me the following error:

-10 Nothing interesting in the update (wrong platform?)

How can I debug/overcome this issue ?

Thanks

That tutorial is outdated.
You should follow VCON::Docs.