Why Can\'t I POST Large Non-Binary Data via AJAX?

Understanding PHP/Apache/AJAX POST Data Limits

Question:

Unable to POST large non-binary data via AJAX, receiving a blank result in PHP with an error indicating an undefined $_POST element.

Code:

// JavaScript
$.ajax({
    data: {'data_string': string}
});

// PHP
$_POST['data_string']

Analysis:

A comprehensive investigation of potential limits that may be hindering the POST process is necessary to resolve this issue.

Points to Consider:

• Apache: LimitRequestBody restricts the size of the HTTP request body received by Apache. Usually set to 2GB, but specific values can vary.

• PHP: Several parameters influence POST data handling:

  • post_max_size: Limits the amount of POST data that can be accepted.
  • upload_max_filesize: Sets the maximum size for file uploads.
  • max_input_time: Specifies the maximum time allowed for POST data input.
  • max_input_nesting_level: Limits the nesting levels of complex arrays in POST data.
  • memory_limit: Constrains the memory available to PHP, which can impact large POST data processing.
  • max_input_vars: Limits the number of variables allowed in POST data.

• Other Factors:

  • Proxy Servers: Proxies may impose their own limits on request body size.
  • Client-Side Browsers: Browser capabilities can affect the size of POST data that can be sent.

Solution:

To resolve this issue, check each of these limiting parameters within Apache, PHP, and other involved components. Ensure they exceed the size of the POST data being transmitted.

If the built-in Apache limit is exceeded, consider breaking the large data into smaller chunks and transmitting them in stages.

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