Update: As of 7:30PM ET Microsoft now says the issue has been addressed and everything should be okay
If you have Windows 10 Mobile installed and are currently experiencing issues with Cortana you are not alone. Many Windows Central readers have tipped us that Cortana is now crashing when it uses text inputs for searches (voice work just fine).
The issue seems to be affecting owners of the Lumia 950 the most. However, members of our forums have also reported that the same crash bug is occurring on other phones like the Lumia 920, 925, and the HTC One M8, which have Windows 10 Mobile installed. We have contacted Microsoft to find out if they are aware of this problem and if they are working to solve it.
The issue is almost certainly a backend server one, which is the good news. A fix could come at any moment and make the whole thing go away. The bad news is, well, it is New Year's Eve (meaning many Microsoft employees are likely off), and this error demonstrates just how fragile a Cortana update on the server side could be.
We'll update this article if any new information comes forward.
Thanks to everyone who tipped us along with our forum members!