Computer Care Associates

After directly replacing just the icon location (changing sites/example to sites/default and nothing else) in the theme settings (global and theme-specific) of a site recently updated from Drupal 5 to Drupal 6, the menu for the site disappeared with array_merge errors in two lines in the ./includes/theme.inc file.

Going to the global theme settings and resaving the variables (which were all missing, no checkboxes marked) fixed the problem.

Strange. But true!

Resolution

If, like Agaric, you're moving from multisite to separate installations for each site (or vice versa) you may find your user-uploaded file paths changing. Drag.

The solution is updating your database, and you can replace part of the file path with straight SQL:

UPDATE files SET filepath = REPLACE(filepath, "sites/help4computers.com/files/", "sites/default/files/")

Upgrading a theme from Drupal 5 to Drupal 6, Agaric ran across this lovely fatal error:

Fatal error: Call to undefined function menu_item_link() in /sites/example/www/sites/default/themes/agaric_custom_theme/template.php on line 15

And indeed, menu_item_link ends with Drupal 5: http://api.drupal.org/api/function/menu_item_link/5

When taking over a site it's always good to check for any domain names the client might have forgotten about. Although shared hosting (or managing multiple clients on a dedicated server as Agaric does) will show all the domains pointing to a single IP address, it's still a useful way to look through and see which may be related, and should follow the site to its new home.

A number of services will do this for you. A good free one is:
http://www.myipneighbors.com/

Resolution