if you are using bitpay whmcs module you will have problem after upgrading your whmcs to version 6.0
your clients will see this error when they want to pay invoices.
Warning: include(../../dbconnect.php): failed to open stream: No such file or directory in /home/username/public_html/modules/gateways/bit-pay/createinvoice.php on line 2
to solve this problem you should change some details in this file createinvoice.php
find this file from address below
and change this line
and your problem will be solve.