Hi @songyang121718,
On possible explanation could be because you don’t have your permissions set correctly:
https://docs.pkp.sfu.ca/admin-guide/en/securing-your-system#file-permissions
In the case of HTTP errors, it is best to check your PHP error log. Please see this post: How do I find my PHP error log?, if you’re unsure about how to go about that.
You can post the output from your error log here, and typically that provides more clues as to what the specific issue that is causing this is.
-Roger
PKP Team