Browser could not read filename which contains special characters

The problem is that you should not upload files with special characters in it. What I use in a plugin of mine is the filter sanitize_file_name.

I ended up pulling and adapting 3 functions from this plugin, so as to do a full clean up of uploaded filenames, so as not to have this kind of error:

add_filter( 'sanitize_file_name', 't5_sanitize_filename', 10 );/** * Clean up uploaded file names *  * Sanitization test done with the filename: * ÄäÆæÀàÁáÂâÃãÅåªₐāĆćÇçÐđÈèÉéÊêËëₑƒğĞÌìÍíÎîÏïīıÑñⁿÒòÓóÔôÕõØøₒÖöŒœßŠšşŞ™ÙùÚúÛûÜüÝýÿŽž¢€‰№$℃°C℉°F⁰¹²³⁴⁵⁶⁷⁸⁹₀₁₂₃₄₅₆₇₈₉±×₊₌⁼⁻₋–—‑․‥…‧.png * @author toscho * @url    https://github.com/toscho/Germanix-WordPress-Plugin */function t5_sanitize_filename( $filename ){    $filename    = html_entity_decode( $filename, ENT_QUOTES, 'utf-8' );    $filename    = t5_translit( $filename );    $filename    = t5_lower_ascii( $filename );    $filename    = t5_remove_doubles( $filename );    return $filename;}/** * Converts uppercase characters to lowercase and removes the rest. * https://github.com/toscho/Germanix-WordPress-Plugin * * @uses   apply_filters( 'germanix_lower_ascii_regex' ) * @param  string $str Input string * @return string */function t5_lower_ascii( $str ){    $str     = strtolower( $str );    $regex   = array(        'pattern'        => '~([^a-z\d_.-])~'        , 'replacement'  => ''    );    // Leave underscores, otherwise the taxonomy tag cloud in the    // backend won’t work anymore.    return preg_replace( $regex['pattern'], $regex['replacement'], $str );}/** * Reduces repeated meta characters (-=+.) to one. * https://github.com/toscho/Germanix-WordPress-Plugin * * @uses   apply_filters( 'germanix_remove_doubles_regex' ) * @param  string $str Input string * @return string */function t5_remove_doubles( $str ){    $regex = apply_filters(            'germanix_remove_doubles_regex'            , array(                'pattern'        => '~([=+.-])\\1+~'                , 'replacement'  => "\\1"            )    );    return preg_replace( $regex['pattern'], $regex['replacement'], $str );}    /** * Replaces non ASCII chars. * https://github.com/toscho/Germanix-WordPress-Plugin * * wp-includes/formatting.php#L531 is unfortunately completely inappropriate. * Modified version of Heiko Rabe’s code. * * @author Heiko Rabe http://code-styling.de * @link   http://www.code-styling.de/?p=574 * @param  string $str * @return string */function t5_translit( $str ){    $utf8 = array(        'Ä'  => 'Ae'        , 'ä'    => 'ae'        , 'Æ'    => 'Ae'        , 'æ'    => 'ae'        , 'À'    => 'A'        , 'à'    => 'a'        , 'Á'    => 'A'        , 'á'    => 'a'        , 'Â'    => 'A'        , 'â'    => 'a'        , 'Ã'    => 'A'        , 'ã'    => 'a'        , 'Å'    => 'A'        , 'å'    => 'a'        , 'ª'    => 'a'        , 'ₐ'    => 'a'        , 'ā'    => 'a'        , 'Ć'    => 'C'        , 'ć'    => 'c'        , 'Ç'    => 'C'        , 'ç'    => 'c'        , 'Ð'    => 'D'        , 'đ'    => 'd'        , 'È'    => 'E'        , 'è'    => 'e'        , 'É'    => 'E'        , 'é'    => 'e'        , 'Ê'    => 'E'        , 'ê'    => 'e'        , 'Ë'    => 'E'        , 'ë'    => 'e'        , 'ₑ'    => 'e'        , 'ƒ'    => 'f'        , 'ğ'    => 'g'        , 'Ğ'    => 'G'        , 'Ì'    => 'I'        , 'ì'    => 'i'        , 'Í'    => 'I'        , 'í'    => 'i'        , 'Î'    => 'I'        , 'î'    => 'i'        , 'Ï'    => 'Ii'        , 'ï'    => 'ii'        , 'ī'    => 'i'        , 'ı'    => 'i'        , 'I'    => 'I' // turkish, correct?        , 'Ñ'    => 'N'        , 'ñ'    => 'n'        , 'ⁿ'    => 'n'        , 'Ò'    => 'O'        , 'ò'    => 'o'        , 'Ó'    => 'O'        , 'ó'    => 'o'        , 'Ô'    => 'O'        , 'ô'    => 'o'        , 'Õ'    => 'O'        , 'õ'    => 'o'        , 'Ø'    => 'O'        , 'ø'    => 'o'        , 'ₒ'    => 'o'        , 'Ö'    => 'Oe'        , 'ö'    => 'oe'        , 'Œ'    => 'Oe'        , 'œ'    => 'oe'        , 'ß'    => 'ss'        , 'Š'    => 'S'        , 'š'    => 's'        , 'ş'    => 's'        , 'Ş'    => 'S'        , '™'    => 'TM'        , 'Ù'    => 'U'        , 'ù'    => 'u'        , 'Ú'    => 'U'        , 'ú'    => 'u'        , 'Û'    => 'U'        , 'û'    => 'u'        , 'Ü'    => 'Ue'        , 'ü'    => 'ue'        , 'Ý'    => 'Y'        , 'ý'    => 'y'        , 'ÿ'    => 'y'        , 'Ž'    => 'Z'        , 'ž'    => 'z'        // misc        , '¢'    => 'Cent'        , '€'    => 'Euro'        , '‰'    => 'promille'        , '№'    => 'Nr'        , '$'    => 'Dollar'        , '℃'    => 'Grad Celsius'        , '°C' => 'Grad Celsius'        , '℉'    => 'Grad Fahrenheit'        , '°F' => 'Grad Fahrenheit'        // Superscripts        , '⁰'    => '0'        , '¹'    => '1'        , '²'    => '2'        , '³'    => '3'        , '⁴'    => '4'        , '⁵'    => '5'        , '⁶'    => '6'        , '⁷'    => '7'        , '⁸'    => '8'        , '⁹'    => '9'        // Subscripts        , '₀'    => '0'        , '₁'    => '1'        , '₂'    => '2'        , '₃'    => '3'        , '₄'    => '4'        , '₅'    => '5'        , '₆'    => '6'        , '₇'    => '7'        , '₈'    => '8'        , '₉'    => '9'        // Operators, punctuation        , '±'    => 'plusminus'        , '×'    => 'x'        , '₊'    => 'plus'        , '₌'    => '='        , '⁼'    => '='        , '⁻'    => '-' // sup minus        , '₋'    => '-' // sub minus        , '–'    => '-' // ndash        , '—'    => '-' // mdash        , '‑'    => '-' // non breaking hyphen        , '․'    => '.' // one dot leader        , '‥'    => '..'  // two dot leader        , '…'    => '...'  // ellipsis        , '‧'    => '.' // hyphenation point        , ' '    => '-'   // nobreak space        , ' '    => '-'   // normal space    );    $str = strtr( $str, $utf8 );    return trim( $str, '-' );}