The PHP verification code is inconsistent with the image.

The PHP verification code is inconsistent with the image. today, I encountered a strange problem. I logged on to the backend a few days ago. Today, the question "the verification code is inconsistent with the image" is displayed when I log on, if both the user name and password are correct, you cannot log on. after checking the information on the Internet, you will find that it is related to the system time. I also try it with a skeptical attitude, because the service PHP verification code is inconsistent with the image

Today, I encountered a strange problem. I logged on to the background a few days ago. today, when I logged on, I encountered the problem of "inconsistent verification codes and Images". the username and password are correct, that is, I could not log on, I checked it online and found that there were few related materials. I also tried it with a skeptical attitude, because the server time is several minutes different from the Beijing time, I changed it and tested it. What is the relationship with system time? In any case, you can log on. thank you.