WordPress: remove acentos e espaços de nomes de arquivos. Mais em http://felipeelia.com.br/wordpress-remover-acentos-e-espacos-de-nomes-de-arquivos/

wordpress-sanitize-filename-on-upload.php

<?php

// Remove acentos e espaços dos arquivos no upload
function custom_sanitize_file_name ( $filename ) {
	$filename = remove_accents( $filename );
	$filename = strtolower( $filename );
	$file_parts = pathinfo( $filename );

	$new_filename = sanitize_title( $file_parts['filename'] );
	if ( ! empty( $file_parts['extension'] ) ) {
		$new_filename = $new_filename . '.' . $file_parts['extension'];
	}
	return $new_filename;
}
add_filter( 'sanitize_file_name', 'custom_sanitize_file_name' );