Finally, I found the answer.

That’s how it works on the Internet

$content = iconv("utf-8","gb2312",$content);

This is the right thing to do. It looks like utf-8 is converted to gb2312, but in practice, it always fails. Why?

The reason is actually quite simple, because any function is executed incorrectly, and unfortunately the iconv(); Then something goes wrong. Here’s the right answer.

The real answer is this

$content = iconv("utf-8","gb2312//IGNORE",$content);

Very simple, just add a //IGNORE after the line, plus this can be ICONV() function IGNORE the error, continue to execute.

Similarly, to replace gb2312 with utf-8, just say $content = iconv(“gb2312”,“utf-8//IGNORE”,$content); just