After a day of exploration, I found that the methods given on the Internet are all unavailable due to the SPAM upgrade, and finally found a way to crack the maintenance certificate. The summary is as follows: The  key to cracking the maintenance certificate is the modification of the program: OCS_CHECK_MAINTENANCE_CERT. , The program cannot be modified. After exploration, I have found a way to modify the program:
1. Create an SAP account (you can copy DDIC permissions), and modify the user group to Developer:

2. Find the program: LSKEYF00 , Remove the edit lock permission;

3. Modify OCS_CHECK_MAINTENANCE_CERT, and modify the sy-subrc value to 0 in the figure below. After the compilation is successful, you are done.

 4. No prompt appears after running rain.

Source : https://blog.titanwolf.in/a?ID=00200-4824cc3b-2d8d-489a-bca2-a5bdc8baf678