网站没有读写权限

PHP Warning:  Unknown: Unable to create temporary file, Check permissions in temporary files directory. in Unknown on line 0
PHP Warning:  Unknown: POST data can't be buffered; all data discarded in Unknown on line 0

如果IIS用户读写权限都给过了，依然不好使，你可以找到PHP.INI文件，修改这个。

upload_tmp_dir = "C:\Windows\Temp"

PHP Warning:  Unknown: Unable to create temporary file, Check permissions in temporary files directory. in Unknown on line 0

PHP Warning:  Unknown: POST data can't be buffered; all data discarded in Unknown on line 0