Server Connection Error - Something went wrong. Try again to send an e-Invoice. Alternatively, you can choose to send a regular invoice without the "Pay Now" Link. I had this same issue and after a lot of trial and error, figured out that it was because my client had a prior merchant account that was replaced with a new merchant account. The invoices that were created while the prior merchant account was active and linked to the QB database would yield the Server Connection Error message while the invoices that were subsequently created after the new and current merchant account was linked to the QB database would not yield that error. The solution was to go back and delete and recreate the invoices that were created under the prior account (can duplicate invoices and delete originals). The recreated invoices were able to send out without the error. Sure wish the error would have been a little more helpful in figuring out the true issue we had.