I’ve had the “500 Internal Server Error” as well & I’m sure there are many reasons that the error may be posted, but for me it was a .htaccess file issue.
My understanding is that the .htaccess file is created when Pretty Permalinks are used. If via your FTP program you can see a .htaccess file, you could either delete it or rename (safer) it. It would be recreated when Pretty Permalinks are set next time.
I’ve made a number of successful installs & upgrades of WP 3.0 but I did have an issue with the WP3.0 zip file available from WP Downloads, I posted that issue here:
Best wishes, Mark
Pleased you got sorted.
As a FYI, I use this paid for solution to backup & move WP sites: http://pluginbuddy.com/purchase/backupbuddy/
Though that won’t help fix a PHP issue, however, this plugin does check server configs: http://pluginbuddy.com/free-wordpress-plugins/serverbuddy/
Regards, Mark
