Warning: preg_match_all() expects parameter 2 to be string

Hello all,

Im getting this error all the time. Does anyone know where it comes from and what I can do about it?

Warning: preg_match_all() expects parameter 2 to be string, array given in /home/users/xxx/xxx/wp-includes/formatting.php on line 229

Warning: array_intersect(): Argument #2 is not an array in /home/users/xxx/xxx/wp-includes/formatting.php on line 230

Warning: preg_split() expects parameter 2 to be string, array given in /home/users/xxx/xxx/wp-includes/formatting.php on line 235

Warning: Invalid argument supplied for foreach() in /home/users/xxx/xxx/wp-includes/formatting.php on line 237

Warning: implode(): Invalid arguments passed in /home/users/xxx/xxx/wp-includes/formatting.php on line 299

These are the line from 229 – 299:

preg_match_all( '@\[/?([^<>&/\[\]\x00-\x20=]++)@', $text, $matches );
	$tagnames = array_intersect( array_keys( $shortcode_tags ), $matches[1] );
	$found_shortcodes = ! empty( $tagnames );
	$shortcode_regex = $found_shortcodes ? _get_wptexturize_shortcode_regex( $tagnames ) : '';
	$regex = _get_wptexturize_split_regex( $shortcode_regex );

	$textarr = preg_split( $regex, $text, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY );

	foreach ( $textarr as &$curl ) {
		// Only call _wptexturize_pushpop_element if $curl is a delimiter.
		$first = $curl[0];
		if ( '<' === $first ) {
			if ( '<!--' === substr( $curl, 0, 4 ) ) {
				// This is an HTML comment delimiter.
				continue;
			} else {
				// This is an HTML element delimiter.

				// Replace each & with & unless it already looks like an entity.
				$curl = preg_replace( '/&(?!#(?:\d+|x[a-f0-9]+);|[a-z1-4]{1,8};)/i', '&', $curl );

				_wptexturize_pushpop_element( $curl, $no_texturize_tags_stack, $no_texturize_tags );
			}

		} elseif ( '' === trim( $curl ) ) {
			// This is a newline between delimiters.  Performance improves when we check this.
			continue;

		} elseif ( '[' === $first && $found_shortcodes && 1 === preg_match( '/^' . $shortcode_regex . '$/', $curl ) ) {
			// This is a shortcode delimiter.

			if ( '[[' !== substr( $curl, 0, 2 ) && ']]' !== substr( $curl, -2 ) ) {
				// Looks like a normal shortcode.
				_wptexturize_pushpop_element( $curl, $no_texturize_shortcodes_stack, $no_texturize_shortcodes );
			} else {
				// Looks like an escaped shortcode.
				continue;
			}

		} elseif ( empty( $no_texturize_shortcodes_stack ) && empty( $no_texturize_tags_stack ) ) {
			// This is neither a delimiter, nor is this content inside of no_texturize pairs.  Do texturize.

			$curl = str_replace( $static_characters, $static_replacements, $curl );

			if ( false !== strpos( $curl, "'" ) ) {
				$curl = preg_replace( $dynamic_characters['apos'], $dynamic_replacements['apos'], $curl );
				$curl = wptexturize_primes( $curl, "'", $prime, $open_sq_flag, $closing_single_quote );
				$curl = str_replace( $apos_flag, $apos, $curl );
				$curl = str_replace( $open_sq_flag, $opening_single_quote, $curl );
			}
			if ( false !== strpos( $curl, '"' ) ) {
				$curl = preg_replace( $dynamic_characters['quote'], $dynamic_replacements['quote'], $curl );
				$curl = wptexturize_primes( $curl, '"', $double_prime, $open_q_flag, $closing_quote );
				$curl = str_replace( $open_q_flag, $opening_quote, $curl );
			}
			if ( false !== strpos( $curl, '-' ) ) {
				$curl = preg_replace( $dynamic_characters['dash'], $dynamic_replacements['dash'], $curl );
			}

			// 9x9 (times), but never 0x9999
			if ( 1 === preg_match( '/(?<=\d)x\d/', $curl ) ) {
				// Searching for a digit is 10 times more expensive than for the x, so we avoid doing this one!
				$curl = preg_replace( '/\b(\d(?(?<=0)[\d\.,]+|[\d\.,]*))x(\d[\d\.,]*)\b/', '$1×$2', $curl );
			}

			// Replace each & with & unless it already looks like an entity.
			$curl = preg_replace( '/&(?!#(?:\d+|x[a-f0-9]+);|[a-z1-4]{1,8};)/i', '&', $curl );
		}
	}

	return implode( '', $textarr );
}