When a transaction layer circuit detects an error, error information in respect of transmission data is set in a TLP digest. The method includes: a step in which, at an endpoint (3a) that receives a memory read request transmitted by the root complex 1, if an error is detected during transmission of first data corresponding to the requested TLP, error information is set in the TLP digest and a completion with data attached is returned; a step in which the root complex (1) returns a memory read request based on the error information to the endpoint; a step in which the endpoint returns requested second data; and a step in which the root complex terminates the response after overwriting the error location of the first data that was held, with the second data.