Is there any reasonable cause for a LED driver to yield more voltage than it is labeled with?
LED drivers are usually constant current power supplies.  This one apparently puts out 300 mA, and is intended to work over the 6-20 V compliance range.

Since it is putting out more than that, the LED is probably presenting a open circuit.  It's no surprise that the voltage is above the range it promises to be able to put out 300 mA.  A ideal constant current supply would go to infinite voltage when presented with a open circuit.  This one apparently limits itself to 38 V.

Try connecting something like a 22 &Omega; power resistor to the output of the supply.  It should go to about (300 mA)(22 &Omega;) = 6.6 V.  It will also dissipate 2 W, so you don't want to hold it there with you fingers too long.

If the power supply works with the resistor test, then the LED or the wires to it are broken.