How to Handle Multiple File Upload in PHP Easily

To handle multiple file uploads in PHP, use the name="files[]" attribute in your HTML form input and loop through the $_FILES['files']['name'] array in PHP. This lets you process each uploaded file individually by accessing its temporary name, error status, and other details.

Why This Happens

When you try to upload multiple files using a single file input without using the array syntax name="files[]", PHP treats it as a single file upload. This causes errors or only one file to be processed.

Also, if you try to access $_FILES['files']['name'] as a string instead of an array, your code will break or ignore other files.

php

<?php
if (isset($_FILES['files'])) {
    // Incorrect: treating as single file
    $fileName = $_FILES['files']['name'];
    move_uploaded_file($_FILES['files']['tmp_name'], 'uploads/' . $fileName);
    echo "Uploaded: " . $fileName;
}
?>

Output

Warning: move_uploaded_file() expects parameter 1 to be string, array given in ...
Only one file uploaded or error occurs.

The Fix

Use name="files[]" in your HTML input to allow multiple files. Then, in PHP, loop through the $_FILES['files']['name'] array to handle each file separately. Check for upload errors and move each file to your desired folder.

php

<form method="POST" enctype="multipart/form-data">
  <input type="file" name="files[]" multiple>
  <button type="submit">Upload</button>
</form>

<?php
if (isset($_FILES['files'])) {
    $totalFiles = count($_FILES['files']['name']);
    for ($i = 0; $i < $totalFiles; $i++) {
        $fileName = $_FILES['files']['name'][$i];
        $tmpName = $_FILES['files']['tmp_name'][$i];
        $error = $_FILES['files']['error'][$i];

        if ($error === UPLOAD_ERR_OK) {
            move_uploaded_file($tmpName, 'uploads/' . $fileName);
            echo "Uploaded: " . htmlspecialchars($fileName) . "<br>";
        } else {
            echo "Error uploading " . htmlspecialchars($fileName) . "<br>";
        }
    }
}
?>

Output

Uploaded: file1.jpg
Uploaded: file2.png
Uploaded: file3.pdf

Prevention

Always use the multiple attribute and name="files[]" in your file input to enable multiple uploads. Validate each file's size and type before saving. Use error checks like UPLOAD_ERR_OK to handle upload problems gracefully. Keep your upload folder secure and avoid overwriting files by renaming if needed.

Related Errors

• Undefined index 'files': Happens if the form input name does not match or form enctype is missing.
• File upload size exceeds limit: Check php.ini settings like upload_max_filesize and post_max_size.
• Permission denied: Ensure the upload folder has write permissions.

Key Takeaways

Use name="files[]" and multiple attribute in HTML to upload multiple files.

Loop through $_FILES['files']['name'] array in PHP to handle each file separately.

Always check for upload errors using UPLOAD_ERR_OK before moving files.

Validate file size and type to keep uploads safe and reliable.

Set correct permissions on the upload folder to avoid permission errors.