What PHP-5.5 Extensions are Required on Magento-1.x Server ?
Apart from php extensions that get installed with php installation itself, following extensions are needed with php5.5 on Magento 1.x server.
php5-curl php5-gd php5-mcrypt
Along with these, you have to install:
Also set date.time zone and increase memory limit in php.ini :
date.timezone = Asia/Kolkata memory_limit = 512M
Enable mcrypt module as:
Now restart the apache2 server:
service apache2 restart