Fatal error on /node/add Drupal8.1.8

Hi there,
I have been adding content from an old HTML site to my Drupal 8.1.8 install and added sever hundered pages. Suddenly I get a error message "The website encountered an unexpected error. Please try again later." for any page node add ( but not node/add/article)

Logs give warning and two error messages
Warning: Error while sending QUERY packet. PID=1366 in Drupal\Core\Database\Statement->execute() (line 59 of /var/www/vhosts/esp.andalucia.ws/httpdocs/core/lib/Drupal/Core/Database/Statement.php).

and

Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: CREATE TABLE {cache_menu} ( `cid` VARCHAR(255) BINARY CHARACTER SET ascii COLLATE ascii_general_ci NOT NULL DEFAULT '' COMMENT 'Primary Key: Unique cache ID.', `data` LONGBLOB NULL DEFAULT NULL COMMENT 'A collection of data to cache.', `expire` INT NOT NULL DEFAULT 0 COMMENT 'A Unix timestamp indicating when the cache entry should expire, or -1 for never.', `created` DECIMAL(14, 3) NOT NULL DEFAULT 0 COMMENT 'A timestamp with millisecond precision indicating when the cache entry was created.', `serialized` SMALLINT NOT NULL DEFAULT 0 COMMENT 'A flag to indicate whether content is serialized (1) or not (0).', `tags` LONGTEXT NULL DEFAULT NULL COMMENT 'Space-separated list of cache tags for this entry.', `checksum` VARCHAR(255) CHARACTER SET ascii COLLATE ascii_general_ci NOT NULL COMMENT 'The tag invalidation checksum when this entry was saved.', PRIMARY KEY (`cid`), INDEX `expire` (`expire`) ) ENGINE = InnoDB DEFAULT CHARACTER SET utf8mb4 COMMENT 'Storage for the cache API.'; Array ( ) in Drupal\Core\Menu\MenuTreeStorage->loadTreeData() (line 848 of /var/www/vhosts/esp.andalucia.ws/httpdocs/core/lib/Drupal/Core/Menu/MenuTreeStorage.php).

and

Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away: CREATE TABLE {cache_config} ( `cid` VARCHAR(255) BINARY CHARACTER SET ascii COLLATE ascii_general_ci NOT NULL DEFAULT '' COMMENT 'Primary Key: Unique cache ID.', `data` LONGBLOB NULL DEFAULT NULL COMMENT 'A collection of data to cache.', `expire` INT NOT NULL DEFAULT 0 COMMENT 'A Unix timestamp indicating when the cache entry should expire, or -1 for never.', `created` DECIMAL(14, 3) NOT NULL DEFAULT 0 COMMENT 'A timestamp with millisecond precision indicating when the cache entry was created.', `serialized` SMALLINT NOT NULL DEFAULT 0 COMMENT 'A flag to indicate whether content is serialized (1) or not (0).', `tags` LONGTEXT NULL DEFAULT NULL COMMENT 'Space-separated list of cache tags for this entry.', `checksum` VARCHAR(255) CHARACTER SET ascii COLLATE ascii_general_ci NOT NULL COMMENT 'The tag invalidation checksum when this entry was saved.', PRIMARY KEY (`cid`), INDEX `expire` (`expire`) ) ENGINE = InnoDB DEFAULT CHARACTER SET utf8mb4 COMMENT 'Storage for the cache API.'; Array ( ) in Drupal\Core\Config\CachedStorage->readMultiple() (line 105 of /var/www/vhosts/esp.andalucia.ws/httpdocs/core/lib/Drupal/Core/Config/CachedStorage.php).

Anybody have any ideas?

Thanks