[Migrating from WHMCS - Import Errors]

I had the same error.

I opened the file, blesta\plugins\import_manager\components\migrations\whmcs\8.0\whmcs8_0.php and everywhere where there was a 
 

catch (Exception $e) {

I added a
 

 echo $e->getMessage();

 

This gave me the correct error messages why it didn't go (I had debug checked as well)
2 errors stopped my, duplicate email address (i had a customer email on an account and as a contact on another account) and a company name too long.

I also changed the Create client section to print the vars array:
 

            // Create client
            $client_id = null;
            try {
                $vars = [
                    'id_format' => '{num}',
                    'id_value' => $client->id,
                    'user_id' => $user_id,
                    'client_group_id' => $this->mappings['client_groups'][$client->groupid],
                    'status' => strtolower($client->status) == 'closed' ? 'inactive' : 'active'
                ];
			print_r($vars); //added this so I can the the whmcs ID of the problem account

 

Once I fixed the 2 accounts the Import went smooth (for the accounts, it didn't import any services yet, troubleshooting that next ... ?

Hope this helps.

I am not sure if there are any log files around that would have contained that information. 
I just installed Blesta to give it a try yesterday ...