This message is generated when the scale of a numerical result is smaller than the scale of numbers that can be represented in the version of the Wolfram Language that is in use.
This message is generated by arithmetic underflow within numerical functions.
The smallest number that can be represented in a particular version of the Wolfram Language can be found by evaluating $MinNumber.
Off[message] switches off the message; On[message] switches it on. For example: Off[General::unfl].
Examples
Basic Examples(1)
The result is smaller than the value of $MinNumber on this computer: