Problems With This Explanation
There are at least two difficulties with this explanation. The first is that it doesn't fully account for the spread of April Fools' Day to other European countries. The Gregorian calendar was not adopted by England until 1752, for example, but April Fools' Day was already well established there by that point. The second is that we have no direct historical evidence for this explanation, only conjecture, and that conjecture appears to have been made more recently