Upgrading to wordpress MU manually from an old blog.

At work I had to update an old wordpress installation from 2.3.2 all the way up to the latest version of WordPress Mu (Multi User).

I documented the method I used and placed it below here.
If you do decide to do this it is done entirely at your own risk.
ALWAYS MAKE A BACKUP FIRST

Stage 1

Install Mu on its own database alongside your existing installation and database, within its own directory in the normal way.

Stage 2

Move the data across from Mu performing an upgrade, keeping all the data intact and wordpress Mu functioning correctly.

How this is done

1. On your old blog`s database rename the following tables

	from				       to
	-----------------------------------------------------------------
	wp_comments		       wp_1_comments
	wp_links			       wp_1_links
	wp_options		       wp_1_options
	wp_postmeta		       wp_1_postmeta
        wp_posts		               wp_1_posts
	wp_terms			       wp_1_terms
	wp_term_relationships       wp_1_term_relationships
	wp_term_taxonomy	       wp_1_term_taxonomy

2. Copy only these tables across from the MU database to the old blog database.

	wp_blogs
	wp_blog_versions
   -->	wp_posts 		(THIS CAN BE OVER WRITTEN BECAREFULL)
	wp_registration_log
	wp_signups
	wp_site
	wp_site_categories

3. Alter the table wp_users in the old database by adding the following fields to its structure

	Field		        Type		  Collation	  Attributes	Null   	default   Extra
	----------------------------------------------------------------------------------------------------------------------
	spam 		tinyint(2)					        No	        0
	deleted		tinyint(2)					        No	        0

4. Add the following information into the table wp_1_options in the old database

	option_id	blog_id		option_name			option_value			        autoload
	--------------------------------------------------------------------------------------------------------------------------------------------
	75		0		avatar_default			        mystery				        yes
	68		0		avatar_rating			        G				                yes
	84		0 		close_comments_days_old		14				                yes
	83		0		close_comments_for_old_posts	0				                yes
	88		0 		comments_per_page		        50				                yes
	116		0		current_theme			        (the value from the database)	yes
	107		0		dashboard_widget_options   	(the value from the database)	yes
	97		0		dismissed_update_core		a:0:{}				                yes
	76		0		enable_app			        0				                yes
	77		0		enable_xmlrpc			        0				                yes
	99		0		fileupload_url			        (the value from the database)	yes
	82		0		image_default_align						                        yes
	80		0		image_default_link_type		file				                yes
	81		0		image_default_size						                        yes
	79		0		large_size_h			        1024				                yes	
	78		0		large_size_w			        1024				                yes
	74		0		medium_size_h			        300				                yes
	73		0		medium_size_w			        300				                yes
	108		0		nonce_salt			                (the value from the database)	yes
	87		0		page_comments			1				                yes
	100		0		post_count			        1				                yes
	61		0		random_seed			        (the value from the database)	yes
	67		0		show_avatars			        1				                yes
	92		0		sticky_posts			        a:0:{}				                yes
	85		0		thread_comments			0				                yes
	86		0		thread_comments_depth		5				                yes
	72		0		thumbnail_crop			        1				                yes
	71		0		thumbnail_size_h		        150				                yes
	70		0		thumbnail_size_w		        150				                yes
	106		0		update_themes			        (the value from the database)	yes
	69		0		upload_url_path							                        yes
	91		0		use_ssl				        0				                yes
	95		0		widget_rss			                a:0:{}				                yes
	94		0		widget_text			        a:0:{}				                yes
	102		0		WPLANG								                        yes
	98		0		wp_1_user_roles			(the value from the database)	yes

5. alter the value of upload_path in wp_1_options in the old database to wp-content/blogs.dir/1/files

The blog will now be active

…but the back office is broken!, to fix this….

6. in wp_usermeta change every entry of wp_capabilities to wp_1_capabilities (use the mysql below)

UPDATE wp_usermeta SET meta_key='wp_1_capabilities' WHERE meta_key='wp_capabilities'

7. create some extra fields based upon the user (run the php code below)

// custom code for upgrade

list($maxId) = $wpdb->get_results( 'SELECT max(umeta_id) AS startPoint FROM wp_usermeta', ARRAY_A);
foreach ($wpdb->get_results( 'SELECT ID FROM wp_users', ARRAY_A) AS $userId){

	echo '
Updating user: '.$userId['ID'].'
';

	// execute all the querys
	for ($queryNumber=0; $queryNumber<3;){
	
		switch ($queryNumber){
			case 0: 
				$SQL1 = "INSERT INTO wp_usermeta (umeta_id, user_id, meta_key, meta_value) VALUES ("; 
				$SQL2 = ", ".$userId['ID'].", 'comment_shortcuts', 'false');"; 
				$queryNumber++; 
				break;
			case 1: 
				$SQL1 = "INSERT INTO wp_usermeta (umeta_id, user_id, meta_key, meta_value) VALUES ("; 
				$SQL2 = ", ".$userId['ID'].", 'admin_color', 'fresh');"; 
				$queryNumber++;
				break;
			case 2: 
				$SQL1 = "INSERT INTO wp_usermeta (umeta_id, user_id, meta_key, meta_value) VALUES ("; 
				$SQL2 = ", ".$userId['ID'].", 'source_domain', 'YOURBLOGDOMAIN');"; 
				$queryNumber++;
				break;
			default:
				die('Query out of bounds exception:  '.$queryNumber);
			}
	
		// check the slot is available
		$check = $wpdb->get_results('SELECT * FROM wp_usermeta WHERE umeta_id='.$maxId['startPoint'], ARRAY_A);
		while (!empty($check)) { 
			$maxId['startPoint']++; 
			echo 'Incrementing to: '.$maxId['startPoint'].'
';
			$check = $wpdb->get_results('SELECT * FROM wp_usermeta WHERE umeta_id='.$maxId['startPoint'], ARRAY_A);
			}
	
		$SQL = $SQL1.$maxId['startPoint'].$SQL2;
		echo 'Executing query '.$queryNumber.'       : ';
		
		echo $wpdb->query($SQL) ? 'Success': 'Failed';
		echo '
';		
		}
	echo '
';
	}

8. point the MU config.php to the old database, you will need to change the permissions from 644 to 666 use CHMOD
or duplicate the config file, alter it, rename the old config file, and then rename the new file as config.php

9. Log into the back office goto to settings->permalinks and click save, your posts/pages can now be found

Your upgrade should now be complete and you can go ahead and delete the MU database installation, not your old but now upgraded database.

I will be happy to answer any questions, and comments as always, are welcome

Additionally:
Ensure that both the field umeta_id in table wp_usermeta and the field ID in table wp_users are set to auto_increment.