While updating your system using pull (as per Staying_up_to_date), your system binaries will be updated. But your kernel does not automatically get updated, and as a result you may encounter problems. For example, in May 2014, a new system call was added to the kernel and some system binaries were recompiled to make use of this system call. Executing those binaries without having a recent kernel could result in an error.

UPDATING YOUR KERNEL

To solve this problem, you will need to reboot your system using the updated kernel that you have pulled. After you have pulled, you can switch to the latest kernel by executing the following:

term% 9fat:
term% cp /386/9pcf /n/9fat
term% fshalt
prompt:  ^t^tr

Optionally, make a backup copy of your old kernel beforehand.