Thank you so much for the recommendation. I had been trying with a more recent version of ElkArte, however I'm still having an issue I've been trying to debug. Please let me know if I should start a new thread instead.
Sorry, the database connection information used in the specified installation of your forum cannot access the installation of phpBB3. This may either mean that the installation doesn't exist, or that the MySQL account used does not have permissions to access it.
The error MySQL gave was: Incorrect database name '''
error_line 351
error_file /var/apps/convert/OpenImporter/Importer.php
I've received this error on both my local development server, and when running on the production server.
protected function testTable()
{
if ($_REQUEST['start'] == 0 && empty($_GET['substep']) && ($_GET['step'] == 1 || $_GET['step'] == 2))
{
$query='
SELECT COUNT(*)
FROM ' . $this->config->from_prefix . $this->config->source->getTableTest();
$result = $this->db->query($query, true);
echo $query;//die();
if ($result === false)
throw new \Exception($this->lng->get(array('permission_denied', $this->db->getLastError(), (string) $this->xml->general->name)));
$this->db->free_result($result);
}
}
It's happening here in test table.
SELECT COUNT(*) FROM ``.users
This is the query that is formed. I'm guessing the database name goes in there at ``, but I've never used a SQL connection that isn't associated with a single database. I'm embarrassed to say I didn't know it was possible outside the MYSQL command line 
protected function init_db()
{
try
{
list ($db_server, $db_user, $db_passwd, $db_persist, $db_prefix, $db_name) = $this->config->destination->dbConnectionData();
print_r($this->config->destination->dbConnectionData());
$this->db = new Database($db_server, $db_user, $db_passwd, $db_persist);
Further down in init_db is getting the database settings. I dumped them just to check what we're getting.
Array ( [0] => localhost [1] => dp_forum [2] => 12345 [3] => [4] => elkarte_ [5] => dp_forum )
All of this is correct for my development box.
if (strpos($db_prefix, '.') === false)
{
// @todo ???
if (is_numeric(substr($db_prefix, 0, 1)))
$this->config->to_prefix = $db_name . '.' . $db_prefix;
else
$this->config->to_prefix = '`' . $db_name . '`.' . $db_prefix;
}
else
{
$this->config->to_prefix = $db_prefix;
}
$this->config->from_prefix = $this->config->source->getPrefix();
if (preg_match('~^`[^`]+`.\d~', $this->config->from_prefix) != 0)
{
$this->config->from_prefix = strtr($this->config->from_prefix, array('`' => ''));
}
Further down in init_db() there's some handling of the to/from_prefix. I don't quite get what it does. Let's see what happens if I force the database name.
$query='
SELECT COUNT(*)
FROM dp_forum.users'; //. $this->config->from_prefix . $this->config->source->getTableTest();
Message: Undefined variable: current
Trace: Undefined variable: current
Line: 521
File: C:\laragon\www\importer\OpenImporter\Importer.php
Message: Undefined variable: current
Trace: Undefined variable: current
Line: 523
File: C:\laragon\www\importer\OpenImporter\Importer.php
Lots of these in a loop.
Unsuccessful!
This query:
SHOW TABLES
FROM ``
LIKE 'users';
Caused the error:
Incorrect database name ''
Line: 117
File: C:\laragon\www\importer\OpenImporter\Database.php
Getting closer I think. The database name is being wiped out somewhere. I will poke around some more and see if I can just force the correct names for my install and move forward.
Thank you again for getting me started.