There have been a number of users that have experienced issues when upgrading from v126.96.36.199 or lower, to v188.8.131.52 and above. This is primarily due to the driver upgrade that occurs.
The first thing to note is that there are instances when the pool's mount points may take some time to come on line after the initial upgrade. If after an extended period (5 - 10 minutes or so), they have not, try a second reboot before continuing.
If you are still having issues, please see the following.
If after performing the above steps your mount points still have not come up, please contact support.