Fatal Error in wp-admin.php

Hello everyone..

Just wondering if you have seen this error before ? Or what might cause it in general ?

Fatal error: Allowed memory size of 16777216 bytes exhausted (tried to allocate 2 bytes) in /var/www/web390/html/wp-admin/includes/plugin.php on line 4

I am getting this, while activating 5 or more plugins (any plugins).

There is nothing wrong with the plugins, all are working fine on my other servers.

Any clue on this ? : (