: To reach Android 7.1.2, you must use community-built ROMs like LineageOS 14.1 or crDroid
Avoid shady file-hosting websites. Use only trusted forums and repositories. Here are the to find Oppo F1s firmware 7.1.2 : Oppo F1s Firmware Download 7-1-2
Device: Oppo F1s (Model: A1601, A1603) Android Version: 7.1.2 Nougat (ColorOS 3.0) : To reach Android 7
The safest place to get official firmware is from Oppo itself. : To reach Android 7.1.2
I can provide the specific links and tools for your exact situation. Share public link
Android 5.1 (Lollipop) / 6.0 (Marshmallow) ColorOS Version: ColorOS 3.0 Firmware Type: Stock ROM (Flash File) How to Download Oppo F1s Firmware
Many reputable Android community sites host official stock ROMs. These can be good alternatives when official sources are limited: