Solution 1: Fail safe options

From v2.0.2, there is a ‘fail-safe’ mode during backing up.

First check [ ] Files and try backing up. If that also fails, check both [ ] Files & [ ] DB and try again.

Solution 2: If this doesn’t work, then

Increase the PHP memory and time limit by adding these lines to the .htaccess of your WP site

php_value memory_limit 256M
php_value max_execution_time 800


Or edit these values in the php.ini of your WP site

memory_limit = 256M
max_execution_time = 800