In 11.12.0, we have introduced new DNS insights. In order to deploy these new insights appliance looks for around 5GB of space in Transaction data store.
If there is no enough space available, you will end up getting "Internal Server Error" when trying to access the UI after update to 11.12 code.
In order to verify if storage has enough space to deploy these new insights, please perform below steps before upgrade to verify if the device would hit this issue after the upgrade.
Step 1: Go to CLI
a) Execute the command "show storage layout" in the CLI of the device.
If the layout is set to "pktpri" (packet priority), then check space in "Primary Data Volume".
If the layout is set to "metprio" (metric priority),
then check the space in the "Secondary Data Volume" which has been selected to store the Transaction Data.
Step 2: Go to the Web UI
a) Go to Administration-> System Settings-> Storage Configuration-> Data/Space Allocation
b) Click on the "Edit" (pencil icon) at the right most side of the Data Section based on Step 1 above. (Primary if "pktprio", Secondary if "metprio").
c) Then drag the transaction data slider all the way down to the to the minimum.
d) That's the minimum size that you need for your current data areas.
e) Then add 5120 to the minimum value you get from "step d" and that would be the minimum size that's needed for the upgrade to be successful.
f) Once you get to know the minimum size required, click on the "Revert" button at the bottom and check the space available currently.
Step 3: Determination of Space Required
a) If the space available from point f is greater than point e (From Step 2 above), then the upgrade would go fine.
b) If the space available from point f is less than point e (From Step 2 above), then please assign the minimum space to the TDS data as determined in point e of Step 2.