Recently, Luca Todesco released yalu iOS 10 jailbreak now on Beta 4, have you met these errors after jailbreak? Here's the solutions to solve these errors.

1. Fix the iMessage / 4G / FaceTime / LTE:

(1) Download [[Mterminal]] and [[OpenSSH]] and for fun download iFile or Filza from Cydia! 

(2) Open MTerminal and type SU.

(3) Input password for root. Default alpine

(4) Input these commands in order exactly.

chmod 755 /var

chmod 755 /var/mobile

chmod 755 /var/mobile/Library

chmod 755 /var/mobile/Library/Preferences

(5) Reboot iDevice Hold power and home button or volume down button for iPhone 7 for 10 seconds

2. Fix mach_portal not WORKING:

If mach_portal force reboots/crashes your idevice or stuck in white screen then REBOOT

MUST REBOOT EACH TIME IT FAILSMight take 2-4 tries. 

3. Fix Cydia App not INSTALLED:

(1) Delete mach_portal

(2) Reboot iDevice Hold power and home button or volume down button for iPhone 7 for 10 seconds

(3) Follow these jailbreak steps again.

①Open Cydia Impactor.

②Plug in your iDevice into Mac/Windows using a lighting cable not micro or type-c .

③Drag and drop the Yalu Jailbreak IPA File in Cydia Impactor.

④Input your Apple ID and password. If you use two-step verification go Here

⑤Once it's done. Unlock iPhone and you will see a new app mach_portal with no icon.

Click here for more details about iOS 10 jailbreak.