Once a client gave me two files to work on. One of those files was not supported on my PC so I saw one file and another one didn't. That was a big mistake. Then when I worked and submitted the file, the client got angry with me. And then I realized that I was wrong not to look at the given file after seeing his provided file, I fixed his work. Then he was happy. But for my mistake, he gave me a 3-star rating. So freelancers should go as well through the client's description and all the files and then start working.