Casper Network v1.5.3 Release Memo Summary: Casper network v1.5.3 update is a patch release which includes bug fixes, security fixes and some enhancements to the network operations. Informational: There are no high priority or severity defects open for release v1.5.3, however we will be including an enhancement in the next release, where the last_progress of the status endpoint will be updated on every block being executed when in validate mode. Key Changes: 1. In v1.5.3 we fixed a bug, where an existing delegator to a validator, who had exceeded the limit of 1200 delegators per validator was unable to increase their delegation stake to that validator. 1. We addressed an issue in v1.5.3, where post upgrade to v1.5.2 some nodes exhibited slow historical sync, operators would now notice an improvement in performance when historically syncing. 1. We fixed an issue in v1.5.3 where the “chain_get_block_transfers” rpc returned ‘null’ instead of an empty array ‘[]’ , this would manifest when a joiner node is synchronizing historical blocks and the blocks do not have any deploys. This followed the data definition of the JSON RPC, but was unexpected behavior for users who did not read the specifications closely. Earlier when querying the block using the chain_get_block_transfers would return null, this is now changed to [], https://github.com/casper-network/casper-node/pull/4272. 1. We have added a configurable way via the config and chainspec files, to allow for a small amount of clock drift to prevent the deploy acceptor from rejecting deploys that are future dated. The top ceiling value is set in the chainspec and adjustable value in config. 1. We did some optimization in the storage component which fixed a bug - where users were reporting missing transfers. 1. The BlockValidator component has also been enhanced to reduce the number of fetch events. 1. We fixed an issue with users re-delegation, where a user trying to re-delegate under a specific node state, that is when the validator is evicted at the same time as the delegation is being processed, would result in lost funds. 1. Couple of security updates around wasm interpreter backport and use of a private fork of parity-wasm and fixes around overflow conditions during specific reward calculation scenarios have also been added to the release. How do the changes impact Network Operators? 1. There is no impact to network operations and no downtime. The operators may notice an improvement to historical syncing. How do the changes impact Smart contract/dApp/sdk Developers? 1. There is no impact to existing contracts and our contract developers are highly encouraged to test their existing contracts on integration or testnet version of 1.5.3.