C/C++ and similar languages use commas for nearly everything. Ada uses the semi-colon for end of line and end of variable declarations whether they are in a declaration block or in a function or procedure parameter list.
Thus, this error occurs each time you write a function or procedure declaration with commas as in:
There is a reason for using the ';' instead of ','. You may declare multiple variables with the same type one after another as in:
a, b, c: type; (2)
The parser has a much better chance to know for sure what you meant if parameters are separated by semi-colons than commas.