Recently I had some problems with another site that I maintain and I had to move the entire domain to a different physical server, and of course the WordPress installation decided to break along the way. There were various problems, but I would have to sum it up as not being able to access anything in the wp-admin folder. Every time I tried to access the admin side of WordPress, I would receive an internal error 500, along with 403’s. After researching this issue for a while, it turns out my original .htaccess file was not restored. More importantly, the workaround for mod_security was not in my .htaccess file. Adding this to the root .htaccess file fixed the problem with not being able to access the admin interface:
<IfModule mod_security.c> SecFilterEngine Off SecFilterScanPOST Off </IfModule>
I also use the plugin WP-Cache, which can cause problems if you move your WordPress installation; this usually comes up as a php include error: wp-settings.php on line 69. The fix is to remove define(“WP_CACHE”, true); from the wp-config.php file. If that still does not fix the problem, then you might have to remove all of the files created by WP-Cache:
If you recently moved your files to another server or renamed your home directory, then the problem is the symbolic link advanced-cache that is under wp-content. Most FTP programs will not show the link, so you must either delete it from within cPanel’s FileManager or shell into your account and do it that way. You can then usually just deactivate and re-activate the plugin, and when you enable caching, it should recreate the link.
And then there is this problem with WordPress 2.0.5.