AppDesigner won't open an mlapp file written with the same version of MATLAB on another machine

I have an mlapp file that was written on PC "A"; when I try to open it using AppDesigner on PC "B", I get the following error: "The 'STRING' input must be either a char row vector, a cell array of char row vectors, or a string array". What would the source of this error be and how might I correct it?