Fatal error: Allowed memory

I tried to activate W3 Total Cache wordpres plugin and got some b开发者_如何学Pythonlank screen with memory error message. After I deactivated all plugins and set the default WP theme, my front page still says :

« Fatal error: Allowed memory size of 262144 bytes exhausted », although my wp-config contains the line : define('WP_MEMORY_LIMIT', '96M');

How is that possible ?

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I would not set memory limit as -1, you are asking for your host to kick you off the server.

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add this in top of wp-config

ini_set('memory_limit', '-1');