[Moto G 2015 General] lost101:
Frequently Asked Questions:

What is a Factory Firmware Image?

These images are not OTA Updates, and have nothing to do with OTA Updates. These files are digitally signed by Motorola; which is why they can be flashed with a Locked Bootloader.

Please do not offer your OTA Update zips, or dumps of your OTA-Updated system. Also, just because an OTA Update is available, does not mean a corresponding Firmware Image will immediately appear in first post. There can be a delay of

days, weeks or months

between the roll-out of an OTA Update and the availability of a Factory Firmware Image.

Is "X" Firmware Image available?

If you don't find the firmware image you seek in first post; your question has already been answered. What you see - is what is currently available. The firmware image will be added asap. Please be patient.

Can I flash Factory Firmware if my Bootloader is locked?

Yes. However attempting to downgrade to an older version of Android may fail - 'Preflash validation' error. Even with an unlocked Bootloader, downgrading cannot be guaranteed. It's also important to be aware that flashing the wrong Bootloader (bootloader.img) for your model can have serious consequences. Always establish your model of Moto G before flashing.

I get a 'Preflash validation' error when flashing a Firmware Image

The Firmware Image you are trying to flash is too old. You can only flash a firmware image that matches, or is newer than the most recent system version you have had on your phone. However the former scenario can also sometimes return the error. In which case, your options are to wait for an even newer firmware image or unlock Bootloader and flash a ROM zip.

After flashing Firmware Image files phone gets stuck during boot-up | will not load Android?

Refer to the guide. Check you are naming the files correctly, and make sure you are flashing all of the 'sparsechunk' files - not just those mentioned in the tutorial. The 'sparsechunk' commands listed there are not to be copied exactly, different firmware images may have different files.

After flashing Firmware Image I have X problem in Android?

There are no major bugs in these firmware images. Users are either not flashing the firmware properly, or not erasing userdata. If anyone has problems in Android after flashing a firmware image, show me a log of the fastboot flashing process.

Downgrading and OTA Updates

If you downgrade, it is advised to avoid all OTA Updates. These updates can result in a hard-brick (phone will not turn on) if you have a newer Bootloader than the one expected. For example, you have the Marshmallow Bootloader, but have downgraded to Android Lollipop.

How to Disable OTA Updates?

(1) Without Root access

It may be possible to do this via:

Settings > Apps > [swipe left to 'All'] > MotorolaOTA (or something similarly named) > Disable​

(2) With Root access

Google Play Store has many apps that will allow you to 'freeze' the OTA Update service. Titanium Backup is a common example.

Alternatively, with a 'root access' file explorer, you can delete or rename the following files:

/system/etc/security/otacerts.zip

/system/priv-app/3c_ota/3c_ota.apk​

These additional files can be removed or renamed: (If you still get an OTA Update notification)

/system/priv-app/3c_checkin/3c_checkin.apk

/system/priv-app/3c_devicemanagement/3c_devicemanagement.apk

/system/priv-app/3c_notification/3c_notification.apk​