What should I do if a server 500 error suddenly occurs in the Alibaba Cloud host?

The first is that you may have wrongly changed the program in that place in the background, which makes it impossible to read it correctly;

The second is that if you are a new site on the space management page, you have to click a button called write permission, because generally new sites will be restricted.

The third reason is the system. There is a mistake. From its server, connect the database correctly.