A packer deactivation system can include a packer and a safety joint. Activation of the safety joint can prevent setting of the packer. A method for use with a subterranean well can include activating a safety joint in the well, and deactivating a packer connected to the safety joint, in response to the safety joint activating. Another packer deactivation system can include a safety joint and a packer drag block locking mechanism. Activation of the safety joint can operate the drag block locking mechanism, thereby preventing a drag block from displacing in a certain direction relative to a mandrel of a packer.