memory size exhausted??

Contact your host. Ask to have php’s memory_limit increased. Or maybe disable some plugins.

I think there’s a way to increase the memory_limit via .htaccess as well (if apache’s config’d for such madness) but don’t recall the directive off hand.

or is it some lines that mod_rewrite should include??

No, not mod_rewrite.

Especially where you are running wp-mu, which likely has higher memory requirements than WP (though, I still don’t think EITHER should exceed 8-10MB per process!!).

HS is correct, you need your php per-process memory limit increased. I generally go with 32MB, but I understand it likely defaults to 8MB, and most shared hosts try to keep it low to prevent ‘abuse’.

-d

Try adding
php_value memory_limit 32M
to your .htaccess file. Worth a shot.

You can also try adding
ini_set("memory_limit", "32M");
to the top of the upgrade_schema.php file (or whatever file is giving you the troubles). Add it just after the first <?php bit.

is it temporary only for the install or is it needed constantly for operating and adding new presses?

where in WP documentation it says so.