CodeIgniter图片上传报错：提交表单允许的最大文件大小超出

Hey there, let's break down why you're hitting this upload error even though you've set $config['max_size'] = '0' in your CodeIgniter setup. Here are the key fixes to try:

1. Check your HTML form's MAX_FILE_SIZE hidden field #

First off, the error message specifically calls out the submission form, so let's start there. Even if your CodeIgniter config allows large files, if your HTML form has a MAX_FILE_SIZE input set too low, it'll block the upload before it even reaches CodeIgniter.

Add or update this hidden input in your upload form (set the value to a byte count matching your desired max size—for example, 67108864 bytes = 64MB):

<input type="hidden" name="MAX_FILE_SIZE" value="67108864">

Make sure this input comes before your file upload field in the form.

2. Adjust PHP's core upload limits #

CodeIgniter's max_size = 0 means it won't enforce its own size limit, but PHP itself has two critical settings that still cap uploads:

• upload_max_filesize: The maximum size of a single uploaded file
• post_max_size: The maximum size of the entire POST request (this needs to be larger than upload_max_filesize, since the request includes the file plus other form data)

How to update these settings: #

Option A: Edit php.ini

Find your php.ini file (run phpinfo() in a test script to locate it) and set values like:

upload_max_filesize = 64M
post_max_size = 70M

After saving, restart your web server (Apache/Nginx) for changes to take effect.

Option B: Use .htaccess (if you can't edit php.ini)

If you're on shared hosting, add these lines to your project's root .htaccess file:

php_value upload_max_filesize 64M
php_value post_max_size 70M

Option C: Try ini_set (note: may not work for all hosts)

Some PHP settings can't be changed at runtime, but you can test adding this at the top of your controller:

ini_set('upload_max_filesize', '64M');
ini_set('post_max_size', '70M');

Keep in mind this won't work for all server configurations, so .htaccess or php.ini edits are more reliable.

3. Verify CodeIgniter's upload config is applied correctly #

Double-check that your config isn't being overwritten somewhere. After loading the upload library, dump the active config to confirm:

$this->load->library('upload', $config);
var_dump($this->upload->get_config());

Look for the max_size value—if it's not 0, something else is overriding your config (like a different config file or later code changes).

Why does this work in non-PHP apps? #

Non-PHP web apps often use alternative upload mechanisms (like direct cloud storage uploads via JavaScript) that bypass PHP's core upload limits. Since your CodeIgniter app relies on PHP's built-in file handling, it's subject to these server-level constraints.

内容的提问来源于stack exchange，提问作者user8207090