Why can't I upgrade my lumia 920 running win 10 v16 to the latest win version 17

[Windows Central Question]

I upgraded my lumia 920 before microsoft stop the upgrade, but I wanna know why I can't actually upgrade to the latest phone version which is version 1709 on my phone, each time I check for updates, I just can't receive new updates, I downloaded window insider and run it but it get an error message.

 

[abhishek singh21]

you must have upgraded to version 1709 using tools found on xda but the drawback is you will never be able to update further as your lumia is unsupported.