# readBlock(at:) Reads a previously-processed block from disk by its block tree entry. ``` func readBlock(at entry: BlockTreeEntry) -> Block? ``` ## Parameters `entry` The block tree entry pointing to the block. ## Return Value The block, or `nil` on read failure. ## Discussion Returns `nil` when the block index lists the entry but the block body is not on disk — e.g., an in-memory chainstate, a pruned data directory, or an entry from a side chain that was never fully validated.