ld( $key, $group = '' ) {
		$has_old_data = false;
		$key = $this->get_item_key( $key );
		$path = $this->_cache_dir . DIRECTORY_SEPARATOR .
			$this->_get_path( $key, $group );

		$data = $this->_read( $path );
		if ( $data != null )
			return array( $data, $has_old_data );


		$path_old = $path . '_old';
		$too_old_time = time() - 30;

		if ( $exists = file_exists( $path_old ) ) {
			$file_time = @filemtime( $path_old );
			if ( $file_time ) {
				if ( $file_time > $too_old_time ) {
					// return old data
					$has_old_data = true;
					return array( $this->_read( $path_old ), $has_old_data );

				}

				// use old enough time to cause recalculation on next call
				@touch( $path_old, 1479904835 );
			}
		}
		$has_old_data = $exists;

		return array( null, $has_old_data );
	}

	/**
	 * Reads file
	 *
	 * @param string  $path
	 * @return array
	 */
	private function _read( $path ) {
		if ( !is_readable( $path ) )
			return null;

		// make sure reading from cache folder
		// canonicalize to avoid unexpected variants
		$base_path = realpath( $this->_cache_dir );
		$path = realpath( $path );

		if ( strlen( $base_path ) <= 0 ||
				substr( $path, 0, strlen( $base_path ) ) != $base_path ) {
			return null;
		}

		$fp = @fopen( $path, 'rb' );
		if ( !$fp )
			return null;

		if ( $this->_locking )
			@flock( $fp, LOCK_SH );

		$var = '';

		while ( !@feof( $fp ) )
			$var .= @fread( $fp, 4096 );

		@fclose( $fp );

		if ( $this->_locking )
			@flock( $fp, LOCK_UN );

		$headers = array();
		if ( substr( $path, -4 ) == '.xml' ) {
			$headers['Content-type'] = 'text/xml';
		}

		return array(
			'404' => false,
			'headers' => $headers,
			'time' => null,
			'content' => $var
		);
	}

	/**
	 * Deletes data
	 *
	 * @param string  $key
	 * @param string  $group Used to differentiate between groups of cache values
	 * @return boolean
	 */
	function delete( $key, $group = '' ) {
		$key = $this->get_item_key( $key );
		$path = $this->_cache_dir . DIRECTORY_SEPARATOR . $this->_get_path( $key, $group );

		if ( !file_exists( $path ) )
			return true;

		$dir = dirname( $path );
		if ( file_exists( $dir . DIRECTORY_SEPARATOR . '.htaccess' ) ) {
			@unlink( $dir . DIRECTORY_SEPARATOR . '.htaccess' );
		}

		$old_entry_path = $path . '_old';
		if ( ! @rename( $path, $old_entry_path ) ) {
			// if we can delete old entry - do second attempt to store in old-entry file
			if ( ! @unlink( $old_entry_path ) || ! @rename( $path, $old_entry_path ) ) {
				return @unlink( $path );
			}
		}

		@touch( $old_entry_path, 1479904835 );
		return true;
	}

	/**
	 * Key to delete, deletes _old and primary if exists.
	 *
	 * @param unknown $key
	 * @return bool
	 */
	function hard_delete( $key, $group = '' ) {
		$key = $this->get_item_key( $key );
		$path = $this->_cache_dir . DIRECTORY_SEPARATOR . $this->_get_path( $key, $group );
		$old_entry_path = $path . '_old';
		@unlink( $old_entry_path );

		if ( !file_exists( $path ) )
			return true;
		@unlink( $path );
		return true;
	}

	/**
	 * Flushes all data
	 *
	 * @param string  $group Used to differentiate between groups of cache values
	 * @return boolean
	 */
	function flush( $group = '' ) {
		if ( $group == 'sitemaps' ) {
			$config = Dispatcher::config();
			$sitemap_regex = $config->get_string( 'pgcache.purge.sitemap_regex' );
			$this->_flush_based_on_regex( $sitemap_regex );
		} else {
			$dir = $this->_flush_dir;
			if ( !empty( $group ) ) {
				$c = new Cache_File_Cleaner_Generic_HardDelete( array(
						'cache_dir' => $this->_flush_dir .
							DIRECTORY_SEPARATOR . $group,
						'exclude' => $this->_exclude,
						'clean_timelimit' => $this->_flush_timelimit
					) );
			} else {
				$c = new Cache_File_Cleaner_Generic( array(
						'cache_dir' => $this->_flush_dir,
						'exclude' => $this->_exclude,
						'clean_timelimit' => $this->_flush_timelimit
					) );
			}

			$c->clean();
		}
	}

	/**
	 * Returns cache file path by key
	 *
	 * @param string  $key
	 * @return string
	 */
	function _get_path( $key, $group = '' ) {
		return ( empty( $group ) ? '' : $group . DIRECTORY_SEPARATOR ) . $key;
	}

	function get_item_key( $key ) {
		return $key;
	}


	/**
	 * Flush cache based on regex
	 *
	 * @param string  $regex
	 */
	private function _flush_based_on_regex( $regex ) {
		if ( Util_Environment::is_wpmu() && !Util_Environment::is_wpmu_subdomain() ) {
			$domain = get_home_url();
			$parsed = parse_url( $domain );
			$host = $parsed['host'];
			$path = isset( $parsed['path'] ) ? '/' . trim( $parsed['path'], '/' ) : '';
			$flush_dir = W3TC_CACHE_PAGE_ENHANCED_DIR .
				DIRECTORY_SEPARATOR . $host . $path;
		} else
			$flush_dir = W3TC_CACHE_PAGE_ENHANCED_DIR .
				DIRECTORY_SEPARATOR . Util_Environment::host();

		$dir = @opendir( $flush_dir );
		if ( $dir ) {
			while ( ( $entry = @readdir( $dir ) ) !== false ) {
				if ( $entry == '.' || $entry == '..' ) {
					continue;
				}
				if ( preg_match( '~' . $regex . '~', basename( $entry ) ) ) {
					Util_File::rmdir( $flush_dir . DIRECTORY_SEPARATOR . $entry );
				}
			}

			@closedir( $dir );
		}
	}
}
<br />
<b>Fatal error</b>:  Uncaught Error: Class 'W3TC\Cache_File_Generic' not found in /var/www/html/bkr-lopesmachado.com.br/web/wp-content/plugins/w3-total-cache/Cache.php:46
Stack trace:
#0 /var/www/html/bkr-lopesmachado.com.br/web/wp-content/plugins/w3-total-cache/PgCache_ContentGrabber.php(940): W3TC\Cache::instance('file_generic', Array)
#1 /var/www/html/bkr-lopesmachado.com.br/web/wp-content/plugins/w3-total-cache/PgCache_ContentGrabber.php(269): W3TC\PgCache_ContentGrabber-&gt;_get_cache('*')
#2 /var/www/html/bkr-lopesmachado.com.br/web/wp-content/plugins/w3-total-cache/PgCache_ContentGrabber.php(217): W3TC\PgCache_ContentGrabber-&gt;_extract_cached_page(false)
#3 /var/www/html/bkr-lopesmachado.com.br/web/wp-content/advanced-cache.php(37): W3TC\PgCache_ContentGrabber-&gt;process()
#4 /var/www/html/bkr-lopesmachado.com.br/web/wp-settings.php(95): include('/var/www/html/b...')
#5 /var/www/html/bkr-lopesmachado.com.br/web/wp-config.php(107): require_once('/var/www/html/b...')
#6 /var/www/html/bkr-lopesmachado.com.br/web/wp-load.php(50): re in <b>/var/www/html/bkr-lopesmachado.com.br/web/wp-content/plugins/w3-total-cache/Cache.php</b> on line <b>46</b><br />