As of PHP 5.4 support for Sqlite2 has been removed. I have a large web app that was built with sqlite2 as the database backend and thus it exploded when I updated PHP. If you're in a similar situation I've written a few wrapper functions that will allow your app to work whilst you convert the code to sqlite3. 
Firstly convert your DB to an sqlite3 db. 
sqlite OLD.DB .dump | sqlite3 NEW.DB
Then add the following functions to your app:
<?php
function sqlite_open($location,$mode)
{
    $handle = new SQLite3($location);
    return $handle;
}
function sqlite_query($dbhandle,$query)
{
    $array['dbhandle'] = $dbhandle;
    $array['query'] = $query;
    $result = $dbhandle->query($query);
    return $result;
}
function sqlite_fetch_array(&$result,$type)
{
    $i = 0;
    while ($result->columnName($i))
    {
        $columns[ ] = $result->columnName($i);
        $i++;
    }
    
    $resx = $result->fetchArray(SQLITE3_ASSOC);
    return $resx;
}
?>
They're not perfect by any stretch but they seem to be working ok as a temporary measure while I convert the site. 
Hope that helps someone