Here is a typical case of Haworthia hibernation Problem: The withered dried roots.
(Chinese speaker can use google translator, I've checked the result and it is correct. 中文使用者請使用google網頁翻譯)
Normally, gardener will adapt water rationing for those hibernating succulents to avoid rotten root, especially in hot and wet weather. However, a long period of water ration sometime causes problems. The root will dying due to the water shortage. Most haworthia plants will still need you to moisten the soil once a week to keep their root activation. Here is the case:
1. Apparently, there is no visible disease evidence. However, if your haworthia has become a little bit softer than before, you might need to pull it out for a check.(感覺比之前軟一點點)

2. Most of roots are dried. (soft and paper thin.)

3.Cut off those dried roots since they are already dead and spray some diluted bleach solution on it for sanitation. (probably 0.4-0.1%)

4. If the temperature is above 33C, you might need to pack it into a freezer bag with some small holes and let it sleep in the refrigerator(>4C) in the whole summer and regularly, spray some water once every 2 weeks depending on your refrigerator's capability.