Error notification using an external channel

Methods, systems, and devices for error notification using an external channel are described. In some cases, a memory system having a host-driven logical block interface may issue a notification of a detected error using an out of band channel. For example, after receiving a data unit from a host system but prior to storing the data in a memory array of the memory system, the memory system may transmit an acknowledgment to host system to indicate that the data was successfully received. As part of storing the data, the memory system may transfer the data along data paths between various components and perform parity checks at each component. If the memory system detects an error along a data path, the memory system may issue a notification of the error to the host system over the out of band channel.