The Lumia 520 officially supports only Windows Phone 8.1. However, the custom ROM community created tools to force-upgrade it to Windows 10 Mobile.
With stock Windows Phone, 512MB of RAM forces a "Lumia Denim" feature set that disables multitasking. But via , you can bypass these limits. The three main goals of current Lumia 520 modders are: nokia lumia 520 custom rom work
⚠️ The Lumia 520 runs Windows Phone 8/8.1 , not Android. Custom ROMs here are not like Android custom ROMs (LineageOS, etc.). You cannot install Android on a Lumia 520 (except very unstable, outdated experimental ports). This guide covers what is actually possible. The Lumia 520 officially supports only Windows Phone 8
: SIM support is often in progress or broken, sometimes leading to signal loss or IMEI blocking. Installation Prerequisites nokia lumia 520 custom rom work