Hi there
Ok, I had this and a kind whmcs support guy worked it out
SO I had to login to the mysql database and there was an order in there that had somehow become adrift
>>>>>>>
It appears that a client who had a pending order has been deleted directly from the WHMCS database:
https:// my info here then clientssummary.php?userid=297
So to resolve this, you would need to delete the erroneous pending order too:
.`tblorders` WHERE `tblorders`.`id` = 455;
I am not sure how the tech guy found the order but when I deleted the tblorders with id 455 it FIXED IT !
SO not sure how you track the order down and be careful in your DB backup first !
Hope this helps others, it was bugging my need it fixed tendencies lol