Samsung is quite protective of its smartphones and Knox is always there to police any interference with the system. Should you trip the “Knox Flag” for any reason, a good deal of features will stop working on your device and this has kept so many users from rooting their devices. Nevertheless, there is currently a way out for all Samsung Galaxy S8 (Snapdragon) users.
You will need a CSC file which users can download from their device. US phones can get the CSC file from the XDA forum. Follow the step by step procedure to rooting your Galaxy S8 (Snapdragon) HERE. Although this method provides a way around the “Knox Flag”, it could cause all sorts of issues and it usually does. So except you desperately need to root your smartphone, you should probably just pass.
Note that this only works for Snapdragon models and does not work for Exynos models. If the root is successful, some apps like SafetyNet and Magisk will stop working. Also, the battery will not charge beyond 80%.