As I expected, the WordPress.org forums are filled with issues in regard to upgrading and using WordPress 2.5. I would highly suggest most people wait a bit on upgrading until the issues with plugins and themes are dealt with by either new versions of the plugins becoming available, or a new version of WordPress comes out that handles memory a bit better. I’m definitely seeing many people having issues with the “Server 500” error which I believe has much to do with the 8mb php default memory limit. So unless you have to upgrade, you might want to wait awhile.
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