PHP post_max_size overrides upload_max_filesize

Simon picture Simon · Oct 13, 2011 · Viewed 162.9k times · Source

In my site host, I have seen (via phpinfo) that

  • post_max_size = 8Mb
  • upload_max_filesize = 16Mb

This led me to think that I should be able to upload as file as big as 16Mb. However, when I do this through a post method (as normal), post_max_size takes over and declares that I sent too much.

What is the method which permits sending a file as big as 16Mb ? GET - PUT - other ?

Hope someone can clarify this for me.

Simon

Answer

Matthew picture Matthew · Feb 25, 2013

upload_max_filesize is the limit of any single file. post_max_size is the limit of the entire body of the request, which could include multiple files.

Given post_max_size = 20M and upload_max_filesize = 6M you could upload up to 3 files of 6M each. If instead post_max_size = 6M and upload_max_filesize = 20M then you could only upload one 6M file before hitting post_max_size. It doesn't help to have upload_max_size > post_max_size.

It's not obvious how to recognize going over post_max_size. $_POST and $_FILES will be empty, but $_SERVER['CONTENT_LENGTH'] will be > 0. If the client just didn't upload any post variables or files, then $_SERVER['CONTENT_LENGTH'] will be 0.