404 error after sub-directory install and server move

I created a file structure in my new CPanel account that mirrors the file structure on the old host. That is, on the new server, in the www directory of my CPanel account, I created a subdirectory of the same name as the subdirectory where WP is installed on the old server. I copied all WP files from oldserver/www/subdirectory to newserver/www/subdirectory. Then I copied .htaccess and index.php from newserver/www/subdirectory and placed them in root.

I exported the database from the old CPanel/phpMyAdmin account and imported it into the new one. That went off without a hitch and the database is obviously properly connected.

I have double-checked that the home and siteurl entries in the imported database are identical to the original. I’ve also verified that the .htaccess and index.php files in both versions of the site are identical, with one exception, as follows:

In the original root-level index.php was this line:

‘require(‘./subdirectory/wp-blog-header.php’);’

According to the Codex, this is incorrect. I changed it in the new root-level index.php to read:

‘require( dirname(__FILE__ ) . ‘/subdirectory/wp-blog-header.php’);’

(Note: the subdirectory is not actually named ‘subdirectory’.)

I tried changing it back to match the original just in case that was the problem, but the 404 continues no matter which version of that line I use.

Nothing else anywhere in the site files has been changed or renamed.

I had not created the same db username or password. I tried that just now and it didn’t change anything, but I didn’t expect it would since I am not getting any database connection errors.

I also wondered if it was somehow related to DNS propagation. I guess I’ll find out when that is finished. Thanks for your input.