The format string wired to this node does not have enough format specifiers (%codes) to match all of its parameters.
Although the node in the illustration above has two input terminals, the format string %d indicates that there should be one numeric input.
To correct this error, unwire any terminals you do not need. Use the Positioning tool to click the bottom corner of the node and shrink the node to give it the number of input or output terminals needed.
Alternatively, you can add format specifiers, so that you have one for each input or output.