Great question — answering as the UphillTech team:
First try the fix-missing feature sudo apt upgrade --fix-missing Second, try to install headers from the command line: Maybe you just need these specific headers (linux-headers-4.4.0-98-generic): sudo apt install linux-headers-4.4.0-98-generic If that doesn't work, see what kernel type you are using (generic, lowlatency, etc.): uname -r This will return something like "4.15.0-30-generic" or "4.15.0-30-lowlatency". Install/Reinstall the headers that correspond to your kernel type. Eg if it is the generic kernel (most likely): sudo apt install --reinstall linux-headers-generic This will cause the current headers for your current kernel to be automatically installed and upgraded. If above...
Full answer by Joshua Besneatte: https://askubuntu.stackexchange.com/a/1064676 (CC BY-SA 4.0).
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