uprade from 2.0.3.0 tot 3.0

I did instal the upgrade as you prescribe but this is the result
SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data OK Notice: Undefined index: Tables_in_MyNameopencartdb in E:\HostingSpaces\MY name\ipathome.be\wwwroot\install\model\upgrade\1000.php on line 149Notice: Undefined index: Tables_in_MYnameopencartdb in E:\HostingSpaces\MYName\ipathome.be\wwwroot\install\model\upgrade\1000.php
E:\HostingSpaces\Verschaeve\ipathome.be\wwwroot\install\model\upgrade\1000.php on line 149{"error":"Error Code(0): Error: Table 'oc_address' already exists

The lines above several times repeated and at the in this message

Error No: 1050
CREATE TABLE `oc_address` (\r\n `address_id` int(11) NOT NULL AUTO_INCREMENT,\r\n `customer_id` int(11) NOT NULL,\r\n `firstname` varchar(32) NOT NULL,\r\n `lastname` varchar(32) NOT NULL,\r\n `company` varchar(40) NOT NULL,\r\n `address_1` varchar(128) NOT NULL,\r\n `address_2` varchar(128) NOT NULL,\r\n `city` varchar(128) NOT NULL,\r\n `postcode` varchar(10) NOT NULL,\r\n `country_id` int(11) NOT NULL DEFAULT '0',\r\n `zone_id` int(11) NOT NULL DEFAULT '0',\r\n `custom_field` text NOT NULL,\r\n PRIMARY KEY (`address_id`),\r\n KEY `customer_id` (`customer_id`)\r\n) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_general_ci in E:\\HostingSpaces\\Verschaeve\\ipathome.be\\wwwroot\\system\\library\\db\\mysqli.php on line 40"}

No webshop anymore and when I put back my backup nothing appears

What to do?

Has this issue been rectified, so far?