PHP upload file when the file is too large $_FILES empty solution

When I was uploading the image, I suddenly found that one gif image failed to be uploaded. size was 0, and the actual size was 4.66M. You can upload small files, but not large files, look at PHP.INI upload_max_filesize = 2M, the problem is here, modify its value

 
; Maximum allowed size for uploaded files. 
upload_max_filesize = 20M 

Restart under nginx problem resolved.