Summary:Project:Support desk/404 errors after upgrade from 1.15 to 1.20

using IIS MediaWiki - 1.15.1 PHP 5.3.8 (cgi-fcgi) MySQL - 5.0.51b-community-nt process

tried to upgrade to 1.20 from 1.15.1 my info: MediaWiki - 1.15.1 PHP - 5.3.8 (cgi-fcgi) MySQL - 5.0.51b-community-nt process: unpacked tar file to new directory copied all installed extensions, custom skin, localSettings.php,images Swapped the old directory and the new directory. Got 404 error at login. Ran update.php in the maintenance directory...now get 500 internal server error:

ModuleName     FastCgiModule Notification   128 HttpStatus     500 HttpReason     Internal Server Error HttpSubStatus  0 ErrorCode      0 ConfigExceptionInfo Notification EXECUTE_REQUEST_HANDLER ErrorCode The operation completed successfully. (0x0)

tried invalidating ALL extensions in localSettings...same result (500 internal server error) changed permissions on Images folder to write for all users...same result (500 internal server error)

I'm really stuck...can anyone advise me? Thanks very much. Jeff Freund