Wordpress - DB connection error after copying a WordPress Multisite instance to a second location

I solved it & it worked :)

In wp_blogs table ,

Old structure was

Domain : localhost/smart_facility_linux
Path : /

But i changed it to to make it work as follows:

For root site:

Domain : localhost
Path : /smart_facility_linux/

For sub site 1 (any subsite under main site ,I just gave example) :

Domain : localhost
Path : /smart_facility_linux/subsite1/

One thought - when I go to www.example.com/staging/wp-admin it automatically redirects me to www.example.com/wp-admin

Could the redirect from staging.example.com to example.com/staging be conflicting with the existing install?

UPDATE: looks like it could be related to .htaccess issues and complicated domain references in the database

From the WP Codex:

Moving WordPress Multisite

Multisite is far more complicated to move, as the database itself has multiple references to the server name as well as the folder locations.

The best way to move Multisite is to move the files, edit the .htaccess and wp-config.php (if the folder name containing Multisite changed), and then manually edit the database. Search for all instances of your domain name, and change them as needed. This step cannot yet be easily automated. If you're moving Multisite from one folder to another, you will need to make sure you edit the wp_blogs entries to change the folder name correctly.

There is really only one way to do an easy transfer of domain or host that I have found. It works flawlessly for me on single and multisite installations.

1. Export your database to a .sql file. ( I use PHPMyAdmin for this )
2. Create a new copy of the file to be edited with a slightly different name.
3. Open the file in you preferred text editor> ( gedit for example )
4. Run a find/replace on the domain AND absolute path ( /home/username/public_html/ to /home/username/public_html/ ) from production to dev.
5. Save the file.
6. Copy the entire installation to your development directory.

7. Add the following line to your wp-config.php file:

   define('RELOCATE',true);

8. Log in, and save your permalinks settings.

9. Remove the define rule you put in your wp-config.php.