Remove accents from Wordpress uploads. This renames all files and replaces corresponding attachment in WordPress database. You probably use linux in production and might run OS X in development. This helps to avoid possible problems with filenames. To avoid this in future install mu-plugin which hooks in 'sanitize_file_name'

rename-uploads.php

<?php
/*
 * Replace-uploads.php
 * This replaces all accents from your uploads
 * you can run this with wp-cli: $ wp eval-file replace-uploads.php
 */

/**
 * cd to right path before changes
 */
if ( defined('WP_CONTENT_DIR') ) {
  chdir(WP_CONTENT_DIR);
} else {
  chdir(ABSPATH);
}

// Get all uploads
$uploads = get_posts(array(
  'post_type'   => 'attachment',
  'numberposts' => -1,
));

global $wpdb;

// Get upload path
$path = get_option('upload_path');

echo "Found: ".count($uploads)." attachments...\n\n";
echo "This may take a while...\n";
foreach ($uploads as $upload) {
  $replace_name = false;
  foreach ($upload->$guid['_wp_attached_file'] as $index => $file) {
    $full_path = $path.'/'.$file;
    echo "Processing upload (ID:{$upload->ID}): {$full_path}";
    $ascii_file = remove_accents($file);
    $ascii_full_path = $path.'/'.$ascii_file;
    // This replaces main file
    if ($file != $ascii_file) {
      $replace_name = true;
      echo "---> Replacing to: {$ascii_full_path}\n";

      rename($full_path, $ascii_full_path);

      # Replace thumbnails too
      $file_path = dirname($full_path);
      $metadata = unserialize($upload->$guid['_wp_attachment_metadata'][$index]);

      // Correct main file
      $metadata['file'] = $ascii_file;

      foreach ($metadata['sizes'] as $name => $thumbnail) {
        $metadata['sizes'][$name]['file'];
        $thumbnail_path = $file_path.'/'.$thumbnail['file'];
        $ascii_thumbnail = remove_accents($thumbnail['file']);

        // Update metadata on thumbnail so we can push it back to database
        $metadata['sizes'][$name]['file'] = $ascii_thumbnail;

        $ascii_thumbnail_path = $file_path.'/'.$ascii_thumbnail;
        echo "Processing thumbnail: {$thumbnail_path} ---> {$ascii_thumbnail_path}\n";          
        rename($thumbnail_path, $ascii_thumbnail_path);
      }

      $fixed_metadata = serialize($metadata);

      $file_basename = basename($file);
      $replace_file_basename = basename($ascii_file);
      # Replace Database

      ## Replace upload name
      echo "Replacing file name in database...\n";
      $sql = "UPDATE {$wpdb->prefix}postmeta SET meta_value = '{$ascii_file}' WHERE post_id={$upload->ID} and meta_key='_wp_attached_file';";
      $wpdb->query($sql);

      ## Replace thumbnail fields
      echo "Replacing thumbnail names in database...\n";
      $sql = "UPDATE {$wpdb->prefix}postmeta SET meta_value = '{$fixed_metadata}' WHERE post_id={$upload->ID} and meta_key='_wp_attachment_metadata';";
      $wpdb->query($sql);

    } else {
      echo "\n";
    }
  }
}

Where i place this file?

The script worked to change PHP and SQL stuff but left the file names unchanged on my host.

I crafted a little bash script to fix filenames on linux :

find . -type f > uncleaded_list.txt; wp eval "echo remove_accents(\"$(find . -type f)\");" > cleaned_list.txt; paste uncleaded_list.txt cleaned_list.txt > list.txt; xargs -a list.txt -n 2 mv

you need wp cli ofcourse

If anyone stumbles upon this, be careful, it could break you website