I have the same problem. I think you can't install any firmware without the bootloader unlocked.I need install firmware 18.3.C.0.37 to my Xperia D2303 because after this, i can unlock bootloader. I try to found the firmware 18.3.C.0.37 but nothing!!!
Anyone can help me?
I have the same problem. I think you can't install any firmware without the bootloader unlocked.
you can unlock the bootloader on latest version, you don't need to be on 0.37 firmware.
edit: but if you want to install anyway i uploaded it to my drive:
Thanks very much. I also have a Singapore version of the ROM. On the Sony bootloader unlocking page it says "Important note! In order to unlock your Xperia™ M2 you need to be on software version 18.3.C.0.37". I haven't attempted to go ahead with it anyway.
Do you have drivers that work? I can't get any PC nor FlashTool to recognise the M2! (FlashTool doesn't include M2 drivers.) Do you know how I could install the ROM? I want to do so anyway regardless of unlocking the bootloader because I gather the Android 4.4 ROM is faster than the laggy 5.1.1 one currently installed on my M2.
Thanks again for the info. I did install Fastboot and Flashmode drivers as per the tutorial on this site I was following, but FlashTool didn't recognise the M2 on Windows XP nor 7 let alone 10 (I have a lot of old PCs!). I'll try a different USB cable.no problem. if i remember correctly the bootloader unlock page was last updated on late 2014 so that note targeted people who used 4.3 jelly bean at the time. you can unlock bootloader on 0.182.
flashtool includes m2 drivers, you need to install Fastboot and Flashmode drivers. also if you are using Windows 8 and above, you need to disable driver signature check (google it). to install stock roms, this device's forum has plenty of guides. do a little research )
also you don't need to unlock your bootloader to install stock and stock based roms (such as Z5 Style, EagleExperience etc.). if you want to install custom roms (Lineage, RR, etc.) you need to unlock bootloader.
Thanks again for the info. I did install Fastboot and Flashmode drivers as per the tutorial on this site I was following, but FlashTool didn't recognise the M2 on Windows XP nor 7 let alone 10 (I have a lot of old PCs!). I'll try a different USB cable.