The error message occurs with credit card payments.
The customer selects "credit card" as means of payment in the checkout. Based on the 3DS procedure, the bank asks your customer for authentication. If the customer does not continue the process, for example because he does not know the password or has not yet activated the 3DS procedure, the transmission is aborted after ten minutes. A notification is then sent to the merchant with the note "Timeout". This is not an error in the communication between the systems involved, but a scheduled process for terminating uncompleted transaction processes.
Example Error-Code: xxxx0056