Systems and devices can include protocol stack circuitry to perform certain methods, including receiving a flow control unit (flit) header and a transaction layer packet (TLP) payload, the TLP payload comprising a first portion and a second portion, determining that the flit header is free from errors, forwarding the flit header and the first portion of the TLP payload to a link partner based on the flit header being free from errors, identifying that the flit contains an error from the second portion of the TLP payload, and sending a data link layer packet (DLLP) to the link partner to indicate the error in the TLP payload.