All macro errors and warnings are now documented in the SAS 9.4 Macro Language Reference, Third Edition. You can find them here:
Each error or warning entry begins with the text of the message followed by a two-colum table that lists each possible cause and a suggested solution for each cause. Here are samples from each section of the appendix that illustrate how the information is presented.
Let us know if this new feature in the SAS Macro Facility documentation helps you to investigate your own possible cause and solution for any macro error you may be encountering.