upgrade.php?_wp_http_referer=/wp-admin/

I have updated a site and find that I can’t now log in to the admin panel because of the blank white screen.

History –
I downloaded and tested a complete version of the site on a local PC and updated the site manually, with plugins and themes enabled. (I know they should be disabled but it all worked fine) I have run this twice and it is fine – I have no problems at all locally.

I then followed exactly the same path – one I have done dozens of times – and copied the 3.1 files manually to the client site, removed the wp-config file, gone to the main site page in a browser, created the config file, added the DB connection details and wp-config is created and I get to the run install page, and click run install.

http://www.xxx.com/wp-admin/install.php is at the top of the browser but there is a white screen with ‘done’ sniggering at me from the bottom right.

It hasn’t ‘done’, it SHOULD be asking me about the install.

If I press refresh nothing happens and trying to go to wp-admin/ gives me the above error.

The web site appears fine and the pages are all OK and running without any seeming problems. Just no admin page.

I have done a complete reinstall with plugin folders and theme folders moved and empty versions put in place and surprisingly the whole site dies, no web pages at all – not even the twentyten default. Put back the themes directory and the client theme works.

Any thoughts?