I have spent quite a bit of time on the error trying to determine where the error is and I have now narrowed it down to the ispconfig module. There is an error in the multiserver logic where it loops through the results to get the server names from the whmcs tblservers. This is what happens. The module executes the sql Query SELECT servergroup FROM tblproducts WHERE id = <productid> This returns the server group with the ISPConfig servers that you set up in WHMCS. Next the module runs the query to get the serverid's of all the servers in that group. Query SELECT serverid FROM tblservergroupsrel WHERE groupid = <groupid> This query returns an array of server id's. Then the module runs a lookup to get the hostname of each of those servers, except that it does not use the serverid, it always uses id = 1, which results in the wrong server name being passed to ISPConfig. In my instance, the server ids on the test server are 2, 3, 4 and 5. Query SELECT hostname FROM tblservers WHERE id = 1 Query SELECT hostname FROM tblservers WHERE id = 1 Query SELECT hostname FROM tblservers WHERE id = 1 Query SELECT hostname FROM tblservers WHERE id = 1 So it looks like the bug should be pretty simple for the developer to fix and hopefully release an update to very soon.