[Samsung Galaxy A3, A5, A7 (2017) Questions & Answe] AndreLopez360:
Using the Magisk module with the Material Design XPSD worked perfectly on my A7(2017)

Hello! I've never posted on XDA before but since I spent 6 hours yesterday trying to figure out a proper way to do just that so I might as well help. ;)

This worked perfectly for my A720F/DS but it should also work with any A series nougat device. Notice that the MOST important part for this to work in other devices is choosing the correct xposed SDK according to your android system and CPU. Magisk is universal, no need to worry about download one specific for your device.

I'll start with a short summary in case you know a lot about the topic and then proceed to a step-by-step process.

Only the "systemless" AKA Magisk way works flawlessly, it's pretty simple when using the correct files. If you already have Magisk properly installed all you have to do is download the latest "Material Design Xposed Installer" and have active the 24 SDK module from the Magisk Manager app.

STEP 1

ROOT WITH MAGISK AND USE VERITY PATCH TO AVOID KNOX PROBLEMS

1. Put magisk v14.0 and dm-verity patch onto the sdcard in the phone.

Download the latest magisk from here: https://xdaforums.com/apps/magisk/official-magisk-v7-universal-systemless-t3473445

Download the Verity Patch from here: https://xdaforums.com/samsung-a-series-2017/help/how-to-install-magisk-v12-0-root-enable-t3611527 You might need this link later to use S Health...

2. Flash TWRP using Odin - You cand download both here https://xdaforums.com/samsung-a-series-2017/development/xcc-t3591448

Important Note for Installing TWRP on A7 2017: Disable auto-reboot in Odin so that after flashing TWRP it says PASSED but instead of rebooting and Knox un-doing what you just did, you will now attempt to go to download mode again (Vol Down + Home + Power Button) but as soon as the screen goes black (meaning the phone is off) you will instead go to Recovery mode, simply pressing the Vol Up + Home + Power Button.

3. In recovery mode, allow modifications. and under wipe there should be a button to format data. You will need to do this to flash Magisk and dm verity, if not your cellphone will be stuck on a bootloop.

4. Flash Magisk, when the process is done simply go back and flash dm verity. (this order is important)

5. Boot the phone normally, it shouldn't take long but don't worry if it takes up to 5 minutes. (In my case, when only the SAMSUNG logo showed up it would always keep going to a normal boot, but when it said A7 and the other info it would be stuck on a boot loop).

6. Open Magisk Manager app and check if you can download and install modules (it needs storage permission first). It you manage to install modules properly then skip to the next step. If it says Process Error and you can't seem to install modules then make sure you give the app the proper permissions and then on the home page of the app select Install Directly (Recommended), I guess this installs Magisk again or somethins.. This seemed to finally make it work for me. A reboot is necessary.

STEP 2

INSTALL SYSTEMLESS XPOSED FRAMEWORK SDK24 MODULE FROM MAGISK ALONG WITH MATERIAL DESIGN XPOSED INSTALLER APK

1. Get the latest "Material Design Xposed Installer" from here, it shouldn't matter if you immediately install it or install it later (like I did)https://xdaforums.com/xposed/material-design-xposed-installer-t3137758 (I'm 90% sure thats the one I used, if it doesn't work, try the one by Sr.CyanDroid)

2. In the Magisk Manager app, download and install the module XPOSED FRAMEWORK SDK24... It will tell you it installed correctly and reboot, you can double check by going into your Modules section after rebooting and seeing if it show up there... its a weird feeling but if it does show up that already means you successfully installed the xposed framework through Magisk.

3. Install (or just open if you previously installed it) the "Material Design Xposed Installer", it will either tell you it failed to detect Xposed or it will say its all perfect and you will be able to use Xposed normally. In case it says it failed, like it did to me, simply update the xposed app within itself. In my case, there was a notice at the bottom suggesting me to install the newest "Material Design Xposed Installer" and the problem was fixed immediately as I did it.

DONE

Keep in mind that by using this Magisk Method you are avoiding modifying the system partition, meaning its a lot less likely for you to brick your phone while trying different xposed files (apks are the only xposed files you need anyway). I hope this helps you and anyone else with this problem, keep in mind its 4am, and I'm really sleep so somethings MIGHT not be perfect. I also have a busy week coming up so I might not be able to respond any messages any time soon. Cheers!