zcashd/doc/release-notes.md

(note: this is a temporary file, to be added-to by anybody, and moved to
release-notes at release time)

Notable changes
===============

RPC Changes
-----------

- `getdeprecationinfo` has several changes:
  - It now returns additional information about currently deprecated and
    disabled features.
  - A new `end_of_service` object that contains both the block height for
    end-of-service and the estimated time that the end-of-service halt is
    expected to occur. Note that this height is just an approximation and
    will change over time as the end-of-service block height approaches,
    due to the variability in block times. The
    `end_of_service` object is intended to replace the `deprecationheight`
    field; see the [Deprecations](#deprecations) section for additional detail.
  - This RPC method was previously only available for mainnet nodes; it is now
    also available for testnet and regtest nodes, in which case it does not
    return end-of-service halt information (as testnet and regtest nodes do not
    have an end-of-service halt feature.)
- Several `z_sendmany` failures have moved from synchronous to asynchronous, so
  while you should already be checking the async operation status, there are now
  more cases that may trigger failure at that stage.
- The `AllowRevealedRecipients` privacy policy is now required in order to choose a
  transparent change address for a transaction. This will only occur when the wallet 
  is unable to construct the transaction without selecting funds from the transparent 
  pool, so the impact of this change is that for such transactions, the user must specify
  `AllowFullyTransparent`.
- The `estimatepriority` RPC call now always returns -1.

Changes to Transaction Fee Selection
------------------------------------

- The `-sendfreetransactions` option has been removed. This option used to
  instruct the wallet's legacy transaction creation APIs (`sendtoaddress`,
  `sendmany`, and `fundrawtransaction`) to use a zero fee for "small" transactions
  that spend "old" inputs. It will now cause a warning on node startup if used.

Removal of Priority Estimation
------------------------------

- Estimation of "priority" needed for a transaction to be included within a target
  number of blocks has been removed. The `estimatepriority` RPC call now always
  returns -1. The format for `fee_estimates.dat` has also changed to no longer save
  these priority estimates. It will automatically be converted to the new format
  which is not readable by prior versions of the software.

[Deprecations](https://zcash.github.io/zcash/user/deprecation.html)
--------------

The following features have been deprecated, but remain available by default.
These features may be disabled by setting `-allowdeprecated=none`. 18 weeks
after this release, these features will be disabled by default and the following
flags to `-allowdeprecated` will be required to permit their continued use:

- `deprecationinfo_deprecationheight`: The `deprecationheight` field of
  `getdeprecationinfo` has been deprecated and replaced by the `end_of_service`
  object.