zcashd 5.10.0 is a maintenance and security bugfix release, including support for NU6 on Testnet. A further upgrade will be needed for NU6 on Mainnet. All zcashd users should upgrade to this release. Version 5.9.1 will reach end-of-service on September 8.
Other notable updates in 5.10.0:
RPC ChangesA bug in parameter handling has been fixed for the getaddresstxids and getaddressdeltas RPC methods. Previously, leaving the end height unset would cause the start height to be set to zero and therefore ignored.
Platform SupportDebian 10 (Buster) has been removed from the list of supported platforms.
FixesSecurity fixes for vulnerabilities (1, 2) disclosed by Bitcoin Core have been backported to zcashd.