Support

First ask your host to make sure that PHP sessions are working properly on your server. If the PHP session save path is not set, is not writeable or sessions are disabled Joomla! will not work at all.

Then take a look at your configuration.php. It should have a line like this:

        public $session_handler = 'database';

If the value in the right hand reads anything other than database change it per the line above to read 'database'. While Joomla! lets you use other methods to store session values, not all servers support it. If you are restoring to a new server that could be the case.

If this still doesn't help you may want to run the restoration again. Pay attention to the following fields in the Site Setup page:

• The Live site URL is optional and normally not required on the vast majority of hosts. If your site doesn't seem to work properly – e.g. missing pictures, all links resulting in 404 errors, etc – you may want to fill in your site's URL, for example http://www.example.com (include the http:// part, but not a trailing slash or index.php!).
• You will also see two more settings here regarding cookies. Under normal circumstances, both of them should be left empty. You only need to edit them if they are not blank and you are transferring your site to a different directory or domain name. The Cookie domain is the domain name of your site, without the protocol and, usually, without the www part. For example, if you are restoring to http://www.example.com, the Cookie domain is example.com (I will stress that again: there is NO http:// in there!!). The Cookie path is the subdirectory of your site, relative to the domain's root. If you are restoring to the root of a domain, e.g. http://www.example.com, then it is / (a single forward slash). If you are restoring to a subdirectory it's a slash followed by the directory's name. For example, if you're restoring to http://www.example.com/joomla then the Cookie path is /joomla (WITH a leading slash, but WITHOUT a trailing slash).

As I've documented with regards to the cookie settings: if the Cookie domain and/or Cookie path settings are non-empty and do not correspond to the location (domain name and directory) you are restoring your site to, YOU WILL NOT BE ABLE TO LOG IN in the front- or the back-end of your site. On most servers you can just leave them blank (strongly recommended). Be advised that if you request support for this issue you will be ignored because there is nothing we can support you with; you are simply entering the wrong values in these fields. You have to either retry the restoration or edit your configuration.php file and modify the cookie_domain and cookie_path parameters.

I believe that the problem lies with the cookie settings, as I've documented. That's why I advise you to rerun the restoration and pay attention to these fields.

As a side note: if it wasn't obvious, the bullet points and the next paragraph were copied verbatim from the documentation. I realise that the wording would be a bit confusing if regarded as part of my reply to you without the note that they are copied directly from the documentation.