I just had this same problem, and when looking a bit better at my code, i found the problem.
For me, the line that was pointed to in the error message was a method definition line in a class definition file. The problem here is that the definition is specified like a method-call, instead of a method-definition. Assuming this is a non-static method, the first input argument will be an object of the class. In the definition, this now is required to be specified as an input argument. (Previously, apparently, we were allowed to put this first first argument before the method name, even in the definition).
If you change
hr = P.pHR(a, b, c);
hr = pHR(P, a, b, c);
it will probably work, also in previous releases.