错误信息说明

从 PHP 4.2.0 开始，PHP 将随文件信息数组一起返回一个对应的错误代码。该代码可以在文件上传时生成的文件数组中的 error 字段中被找到，也就是 $_FILES['userfile']['error']。

UPLOAD_ERR_OK

其值为 0，没有错误发生，文件上传成功。

UPLOAD_ERR_INI_SIZE

其值为 1，上传的文件超过了 php.ini 中 upload_max_filesize 选项限制的值。

UPLOAD_ERR_FORM_SIZE

其值为 2，上传文件的大小超过了 HTML 表单中 MAX_FILE_SIZE 选项指定的值。

UPLOAD_ERR_PARTIAL

其值为 3，文件只有部分被上传。

UPLOAD_ERR_NO_FILE

其值为 4，没有文件被上传。

UPLOAD_ERR_NO_TMP_DIR

其值为 6，找不到临时文件夹。PHP 4.3.10 和 PHP 5.0.3 引进。

UPLOAD_ERR_CANT_WRITE

其值为 7，文件写入失败。PHP 5.1.0 引进。

Note:

以上值在 PHP 4.3.0 之后变成了 PHP 常量。

User Contributed Notes

viseth10 at gmail dot com 21-Aug-2017 10:31
[Well just a little note. ]
That UploadException class example posted on top by anonymous is great. It works good. But there is a certain problem. You know there are two sides to generating errors.
First -> for the client side.
Second -> for the developers who will use your script

But i see only one side to generating Exceptions. ie For the developers.

Why ? Because when you generate an Exception, your script will come to an halt and do whatever you have defined in catch clause.
Now you dont want any client to see the Exception, do you ? I will not. The client will want to know what error occured in simple words they can understand instead of wanting their web app crashed if upload fails. So,  dont generate exceptions. These errors should be collected and shown to client in an elegant way. That's a little advice.
Keep developing smarter.
Tom 06-Jan-2015 12:29
As it is common to use move_uploaded_file with file uploads, how to get it's error messages should be noted here (especially since it's not noted anywhere else in the manual).
Common code is to do something like:
 if (move_uploaded_file($_FILES["file1"]["tmp_name"], $target_file)) {
      echo "<P>FILE UPLOADED TO: $target_file</P>";
   } else {
      echo "<P>MOVE UPLOADED FILE FAILED!!</P>";
      print_r(error_get_last());
   }
rlerne at gmail dot com 27-Sep-2014 06:11
This updates "adam at gotlinux dot us" above and makes it version aware, and also adds newer constants to the array.

The reason we want to check the version is that the constants are not defined in earlier versions, and they appear later in the array. They would effectively overwrite the "0" index (no error) with an error message when the file actually uploaded fine.

It also drops the constant's value (0,1,2, etc) for the errors, in the likely event that they are changed later (the code should still work fine).

<?php

$upload_errors = array(
    0                        => "There is no error, the file uploaded with success"
    ,UPLOAD_ERR_INI_SIZE    => "The uploaded file exceeds the upload_max_filesize directive in php.ini"
    ,UPLOAD_ERR_FORM_SIZE    => "The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form"
    ,UPLOAD_ERR_PARTIAL        => "The uploaded file was only partially uploaded"
    ,UPLOAD_ERR_NO_FILE        => "No file was uploaded"
);

if (version_compare(PHP_VERSION, '5.0.3') >= 0)
    $upload_errors[UPLOAD_ERR_NO_TMP_DIR] = "Missing a temporary folder";

if (version_compare(PHP_VERSION, '5.1.0') >= 0)
    $upload_errors[UPLOAD_ERR_CANT_WRITE] = "Failed to write to disk";

if (version_compare(PHP_VERSION, '5.2.0') >= 0)
    $upload_errors[UPLOAD_ERR_EXTENSION] = "File upload stopped by extension";
?>
Viktor 17-Sep-2014 06:14
Update to Adams old comment.

This is probably useful to someone.

<?php

$phpFileUploadErrors = array(
    0 => 'There is no error, the file uploaded with success',
    1 => 'The uploaded file exceeds the upload_max_filesize directive in php.ini',
    2 => 'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form',
    3 => 'The uploaded file was only partially uploaded',
    4 => 'No file was uploaded',
    6 => 'Missing a temporary folder',
    7 => 'Failed to write file to disk.',
    8 => 'A PHP extension stopped the file upload.',
);
Jeff Miner mrjminer AT gmail DOT com 10-Aug-2010 10:32
One thing that is annoying is that the way these constant values are handled requires processing no error with the equality, which wastes a little bit of space.  Even though "no error" is 0, which typically evaluates to "false" in an if statement, it will always evaluate to true in this context.

So, instead of this:
-----
<?php
if($_FILES['userfile']['error']) {
  // handle the error
} else {
  // process
}
?>
-----
You have to do this:
-----
<?php
if($_FILES['userfile']['error']==0) {
  // process
} else {
  // handle the error
}
?>
-----
Also, ctype_digit fails, but is_int works.  If you're wondering... no, it doesn't make any sense.

To Schoschie:

You ask the question:  Why make stuff complicated when you can make it easy?  I ask the same question since the version of the code you / Anonymous / Thalent (per danbrown) have posted is unnecessary overhead and would result in a function call, as well as a potentially lengthy switch statement.  In a loop, that would be deadly... try this instead:

-----
<?php
$error_types = array(
1=>'The uploaded file exceeds the upload_max_filesize directive in php.ini.',
'The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form.',
'The uploaded file was only partially uploaded.',
'No file was uploaded.',
6=>'Missing a temporary folder.',
'Failed to write file to disk.',
'A PHP extension stopped the file upload.'
);

// Outside a loop...
if($_FILES['userfile']['error']==0) {
  // process
} else {
  $error_message = $error_types[$_FILES['userfile']['error']];
  // do whatever with the error message
}

// In a loop...
for($x=0,$y=count($_FILES['userfile']['error']);$x<$y;++$x) {
  if($_FILES['userfile']['error'][$x]==0) {
    // process
  } else {
    $error_message = $error_types[$_FILES['userfile']['error'][$x]];
    // Do whatever with the error message
  }
}

// When you're done... if you aren't doing all of this in a function that's about to end / complete all the processing and want to reclaim the memory
unset($error_types);
?>
Tom 09-Aug-2010 12:06
Note: something that might surprise you, PHP also provides a value in the $_FILES array, if the input element has no value at all, stating an error UPLOAD_ERR_NO_FILE.

So UPLOAD_ERR_NO_FILE is not an error, but a note that the input element just had no value. Thus you can't rely on the $_FILES array to see if a file was provided. Instead you have to walk the array and check every single damn entry - which can be quite difficult since the values may be nested if you use input elements named like "foo[bar][bla]".

Seems like PHP just introduced you to yet another common pitfall.
jille at quis dot cx 24-May-2009 05:12
UPLOAD_ERR_PARTIAL is given when the mime boundary is not found after the file data. A possibly cause for this is that the upload was cancelled by the user (pressed ESC, etc).
Anonymous 05-Mar-2009 03:32
[EDIT BY danbrown AT php DOT net: This code is a fixed version of a note originally submitted by (Thalent, Michiel Thalen) on 04-Mar-2009.]


This is a handy exception to use when handling upload errors:

<?php

class UploadException extends Exception
{
    public function __construct($code) {
        $message = $this->codeToMessage($code);
        parent::__construct($message, $code);
    }

    private function codeToMessage($code)
    {
        switch ($code) {
            case UPLOAD_ERR_INI_SIZE:
                $message = "The uploaded file exceeds the upload_max_filesize directive in php.ini";
                break;
            case UPLOAD_ERR_FORM_SIZE:
                $message = "The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form";
                break;
            case UPLOAD_ERR_PARTIAL:
                $message = "The uploaded file was only partially uploaded";
                break;
            case UPLOAD_ERR_NO_FILE:
                $message = "No file was uploaded";
                break;
            case UPLOAD_ERR_NO_TMP_DIR:
                $message = "Missing a temporary folder";
                break;
            case UPLOAD_ERR_CANT_WRITE:
                $message = "Failed to write file to disk";
                break;
            case UPLOAD_ERR_EXTENSION:
                $message = "File upload stopped by extension";
                break;

            default:
                $message = "Unknown upload error";
                break;
        }
        return $message;
    }
}

// Use
 if ($_FILES['file']['error'] === UPLOAD_ERR_OK) {
//uploading successfully done
} else {
throw new UploadException($_FILES['file']['error']);
}
?>
info at foto50 dot com 03-Jul-2007 11:03
For those reading this manual in german (and/or probably some other languages) and you miss error numbers listed here, have a look to the english version of this page ;)
belowtherim2000 at yahoo dot com 21-Jun-2007 03:25
I've been playing around with the file size limits and with respect to the post_max_size setting, there appears to be a hard limit of 2047M.  Any number that you specify above that results in a failed upload without any informative error describing what went wrong.  This happens regardless of how small the file you're uploading may be.  On error, my page attempts to output the name of the original file.  But what I discovered is that this original file name, which I maintained in a local variable, actually gets corrupted.  Even my attempt to output the error code in $_FILES['uploadedfiles']['error'] returns an empty string/value.

Hopefully, this tidbit will save someone else some grief.
svenr at selfhtml dot org 24-Apr-2007 12:15
Clarification on the MAX_FILE_SIZE hidden form field and the UPLOAD_ERR_FORM_SIZE error code:

PHP has the somewhat strange feature of checking multiple "maximum file sizes".

The two widely known limits are the php.ini settings "post_max_size" and "upload_max_size", which in combination impose a hard limit on the maximum amount of data that can be received.

In addition to this PHP somehow got implemented a soft limit feature. It checks the existance of a form field names "max_file_size" (upper case is also OK), which should contain an integer with the maximum number of bytes allowed. If the uploaded file is bigger than the integer in this field, PHP disallows this upload and presents an error code in the $_FILES-Array.

The PHP documentation also makes (or made - see bug #40387 - http://bugs.php.net/bug.php?id=40387) vague references to "allows browsers to check the file size before uploading". This, however, is not true and has never been. Up til today there has never been a RFC proposing the usage of such named form field, nor has there been a browser actually checking its existance or content, or preventing anything. The PHP documentation implies that a browser may alert the user that his upload is too big - this is simply wrong.

Please note that using this PHP feature is not a good idea. A form field can easily be changed by the client. If you have to check the size of a file, do it conventionally within your script, using a script-defined integer, not an arbitrary number you got from the HTTP client (which always must be mistrusted from a security standpoint).
web att lapas dott id dott lv 23-Feb-2007 02:49
1. And what about multiple file upload ? - If there is an UPLOAD_ERR_INI_SIZE error with multiple files - we can`t detect it normaly ? ...because that we have an array, but this error returns null and can`t use foreach. So, by having a multiple upload, we can`t normaly inform user about that.. we can just detect, that sizeof($_FILES["file"]["error"]) == 0 , but we can`t actualy return an error code. The max_file_size also is not an exit, becouse it refers on each file seperatly, but upload_max_filesize directive in php.ini refers to all files together. So, for example, if upload_max_filesize=8Mb , max_file_size = 7Mb and one of my files is 6.5Mb and other is 5Mb, it exeeds the upload_max_filesize - cant return an error, becouse we don`t know where to get that error.
Unfortunately we cannot get the file sizes on client side, even AJAX normaly can`t do that.

2. If in file field we paste something, like, D:\whatever , then there also isn`t an error to return in spite of that no such file at all.
stephen at poppymedia dot co dot uk 27-Sep-2005 12:05
if post is greater than post_max_size set in php.ini

$_FILES and $_POST will return empty
adam at gotlinux dot us 27-May-2005 04:28
This is probably useful to someone.

<?php
array(
        0=>"There is no error, the file uploaded with success",
        1=>"The uploaded file exceeds the upload_max_filesize directive in php.ini",
        2=>"The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form"
        3=>"The uploaded file was only partially uploaded",
        4=>"No file was uploaded",
        6=>"Missing a temporary folder"
);
?>
sysadmin at cs dot fit dot edu 16-Feb-2005 04:13
I noticed that on PHP-4.3.2 that $_FILES can also not be set if the file uploaded exceeds the limits set by upload-max-filesize in the php.ini, rather than setting error $_FILES["file"]["error"]
krissv at ifi.uio.no 28-Jan-2005 01:11
When $_FILES etc is empty like Dub spencer says in the note at the top and the error is not set, that might be because the form enctype isnt sat correctly. then nothing more than maybe a http server error happens.

enctype="multipart/form-data" works fine
Dub Spencer 26-Nov-2004 03:56
Upload doesnt work, and no error?

actually, both $_FILES and $_REQUEST in the posted to script are empty?

just see, if  "post_max_size" is lower than the data you want to load.

in the apache error log, there will be an entry like "Invalid method in request". and in the access log, there will be two requests: one for the POST, and another that starts with all "----" and produces a 501.
tyler at fishmas dot org 04-Nov-2004 04:08
In regards to the dud filename being sent, a very simple way to check for this is to check the file size as well as the file name.  For example, to check the file size simple use the size attribute in your file info array:

<?php
if($_FILES["file_id"]["size"]  == 0)
{
         // ...PROCESS ERROR
}
?>