About 404 error

It's really impossible to suggest anything without showing us some code, share what you've done to debug, share what errors are logged in PHP and/or MySQL, etc.

I really want to share some of it but it doesn't have any error log on php or MYSQL.

And it's not only happen on the page I said but some other page which just loading data from one table sometime.

Sometime it just need to wait from a few mins. and refresh it but sometime it will keep 404 for a day.