I think I can explain the problem.
I think it's because the game program is programmed to look for “readme.txt” text files. If a file with the same name is placed in the same directory as the game program, you'll find that the “about” button in the game automatically recognizes the file, even if it's not the original one. and when there is no “readme.txt” in the same directory as the game program, “about” will choose to report an error.
This is a very funny and interesting phenomenon. The reason it hasn't happened before is that the “readme.txt” text file is in the same zip file as the game program when you update it.