EC-CUBE3.0.7 で不具合が多く
希望するものが 3.0.8 で改善されてそうなので

http://ec-cube.github.io/update.html

に従いアップグレードを試みました

（内容）
以下のディレクトリを上書きする
src/
html/
vendor/
http://インストール先/install.php/migrationにアクセスしマイグレーションを実行
html/install.phpを削除


そもそも migration にアクセスしても 500エラーでした。
ログは下記でした　対処方法教えて頂けませんでしょうか

nginx/1.4.6 (Ubuntu)
PHP 5.5.30-1+deb.sury.org~precise+1
mysql Ver 14.14 Distrib 5.5.46

#1 /var/www/aaa.bbb.com/vendor/doctrine/common/lib/Doctrine/Common/Proxy/AbstractProxyFactory.php(220): Doctrine\Common\Proxy\ProxyGenerator->generateProxyClass(Object(Doctrine\ORM\Mapping\ClassMetadata), '/var/www/store....')
#2 /var/www/aaa.bbb.com/vendor/doctrine/common/lib/Doctrine/Common/Proxy/AbstractProxyFactory.php(119): Doctrine\Common\Proxy\AbstractProxyFactory->getProxyDefinition('Eccube\\Entity\\P...')" while reading response header from upstream, client: 60.97.62.5, server: aaa.bbb.com, request: "GET /index.php/migration HTTP/1.1", upstream: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "aaa.bbb.com"
2016/01/31 22:10:50 [error] 20790#0: *2 FastCGI sent in stderr: "PHP message: PHP Fatal error: Uncaught exception 'Doctrine\Common\Proxy\Exception\UnexpectedValueException' with message 'Your proxy directory "/var/www/aaa.bbb.com/src/Eccube/../../app/cache/doctrine" must be writable' in /var/www/aaa.bbb.com/vendor/doctrine/common/lib/Doctrine/Common/Proxy/Exception/UnexpectedValueException.php:40
Stack trace:
#0 /var/www/aaa.bbb.com/vendor/doctrine/common/lib/Doctrine/Common/Proxy/ProxyGenerator.php(299): Doctrine\Common\Proxy\Exception\UnexpectedValueException::proxyDirectoryNotWritable('/var/www/store....')
#1 /var/www/aaa.bbb.com/vendor/doctrine/common/lib/Doctrine/Common/Proxy/AbstractProxyFactory.php(220): Doctrine\Common\Proxy\ProxyGenerator->generateProxyClass(Object(Doctrine\ORM\Mapping\ClassMetadata), '/var/www/store....')
#2 /var/www/aaa.bbb.com/vendor/doctrine/common/lib/Doctrine/Common/Proxy/AbstractProxyFactory.php(119): Doctrine\Common\Proxy\AbstractProxyFactory->getProxyDefinition('Eccube\\Entity\\P...')" while reading response header from upstream, client: 60.97.62.5, server: aaa.bbb.com, request: "GET / HTTP/1.1", upstream: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "aaa.bbb.com"