I have a rooted Huawei G Play Mini. Boot loader is unlocked. Also, I have custom recovery (TWRP) installed. And, I need to upgrade my phone from lollipop to marshmallow. But, I do not have stock recovery back up. I can't find it anywhere. Tell me where to find it, or tell me how to how to install the official stock rom by using TWRP.
Before you do the upgrade, via TWRP, select backup> the select system, data (if you want yours apps), boot, and recovery. This will backup what is currently installed on your phone. Once this completes, go ahead and install the MM update for your phone. Do this within twrp as well to keep the custom recovery.
Download the rom at http://download-c.huawei.com/download/downloadCenter?downloadId=79304
To install the rom follow instructions at https://huaweiflash.com/how-to-flash-huawei-stock-firmware-all-methods/