SuperSU binaries won't install to my HTC One M8 I am following this guide to root my HTC One M8. I just need root, I don't need a custom ROM.

I have gotten to step 7 (weaksauce). I can install weaksauce fine and it roots my device (at least, it says it roots it).

However, when I try to run SuperSU (downloaded from the Android market, latest version) it says The SU binary needs to be updated. Continue? It says this in my notification bar as well. I click Continue and it says Installing, please wait. If you see this message for more than five minutes please restart and try again. After about 30 seconds, it says Installation failed ! Please reboot and try again.

I've tried it multiple times with all forms of rebooting (adb reboot, holding power button, etc) as well as a factory reset (which put me back down to 4.2.2), however it keeps giving me this error.
I have had this issue and there are 3 ways to try to get around this.

You will need a custom recovery to attempt 1. or you can use Odin alternatively for 2. below. The superSU binaries are often (but not always) installed via recovery and the app itself gives this option.


When superSU asks you to update the binaries, rather than select 'Normal' select 'Recovery' and see if it can install that way.
Flash superSU.zip directly in your recovery or Odin. Here is the link to Chainfire's latest version. I have tried this myself and it fixed the issue for me on a number of devices. 
Install an alternative super user app from the market. (This can be messy, and you need to ensure superSU is completely removed)