How to Upgrade
==============

If you are running an older version, shut it down. Wait until it has completely
shut down (which might take a few minutes for older versions), then run the
installer (on Windows) or just copy over `/Applications/Bitcoin-Qt` (on Mac)
or `bitcoind`/`bitcoin-qt` (on Linux).

If your node has a txindex, the txindex db will be migrated the first time you run 0.17.0 or newer, which may take up to a few hours. Your node will not be functional until this migration completes.

The first time you run version 0.15.0 or newer, your chainstate database will be converted to a
new format, which will take anywhere from a few minutes to half an hour,
depending on the speed of your machine.

Note that the block database format also changed in version 0.8.0 and there is no
automatic upgrade code from before version 0.8 to version 0.15.0. Upgrading
directly from 0.7.x and earlier without re downloading the blockchain is not supported.
However, as usual, old wallet versions are still supported.

Downgrading warning
-------------------

The chainstate database for this release is not compatible with previous
releases, so if you run 0.15 and then decide to switch back to any
older version, you will need to run the old release with the `-reindex-chainstate`
option to rebuild the chainstate data structures in the old format.

If your node has pruning enabled, this will entail re-downloading and
processing the entire blockchain.

Compatibility
==============

Bitcoin Core is extensively tested on multiple operating systems using
the Linux kernel, macOS 10.10+, and Windows 7 and newer (Windows XP is not supported).

Bitcoin Core should also work on most other Unix-like systems but is not
frequently tested on them.

From 0.17.0 onwards macOS <10.10 is no longer supported. 0.17.0 is built using Qt 5.9.x, which doesn't
support versions of macOS older than 10.10.

Known issues
============

- Upgrading from 0.13.0 or older currently results in memory blow-up during the roll-back of blocks to the SegWit activation point. In these cases, a full `-reindex` is necessary.

- The GUI suffers from visual glitches in the new MacOS dark mode. This has to do with our Qt theme handling and is not a new problem in 0.17.0, but is expected to be resolved in 0.17.1.

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

Changed configuration options
-----------------------------

- `-includeconf=<file>` can be used to include additional configuration files.
  Only works inside the `bitcoin.conf` file, not inside included files or from
  command-line. Multiple files may be included. Can be disabled from command-
  line via `-noincludeconf`. Note that multi-argument commands like
  `-includeconf` will override preceding `-noincludeconf`, i.e.
  ```
  noincludeconf=1
  includeconf=relative.conf
  ```

as bitcoin.conf will still include `relative.conf`.

GUI changes
-----------

- Block storage can be limited under Preferences, in the Main tab. Undoing this setting requires downloading the full blockchain again. This mode is incompatible with -txindex and -rescan.

External wallet files
---------------------

The `-wallet=<path>` option now accepts full paths instead of requiring wallets
to be located in the -walletdir directory.

Newly created wallet format
---------------------------

If `-wallet=<path>` is specified with a path that does not exist, it will now
create a wallet directory at the specified location (containing a wallet.dat
data file, a db.log file, and database/log.? files) instead of just
creating a data file at the path and storing log files in the parent
directory. This should make backing up wallets more straightforward than
before because the specified wallet path can just be directly archived without
having to look in the parent directory for transaction log files.

For backwards compatibility, wallet paths that are names of existing data files
in the `-walletdir` directory will continue to be accepted and interpreted the
same as before.

Dynamic loading and creation of wallets
---------------------------------------

Previously, wallets could only be loaded or created at startup, by specifying `-wallet` parameters on the command line or in the bitcoin.conf file. It is now possible to load, create and unload wallets dynamically at runtime:

- Existing wallets can be loaded by calling the `loadwallet` RPC. The wallet can be specified as file/directory basename (which must be located in the `walletdir` directory), or as an absolute path to a file/directory.
- New wallets can be created (and loaded) by calling the `createwallet` RPC. The provided name must not match a wallet file in the `walletdir` directory or the name of a wallet that is currently loaded.
- Loaded wallets can be unloaded by calling the `unloadwallet` RPC.

This feature is currently only available through the RPC interface.

Coin selection
--------------

### Partial spend avoidance

When an address is paid multiple times the coins from those separate payments can be spent separately which hurts privacy due to linking otherwise separate addresses. A new `-avoidpartialspends` flag has been added (default=false). If enabled, the wallet will always spend existing UTXO to the same address together even if it results in higher fees. If someone were to send coins to an address after it was used, those coins will still be included in future coin selections.

Configuration sections for testnet and regtest
----------------------------------------------

It is now possible for a single configuration file to set different
options for different networks. This is done by using sections or by
prefixing the option with the network, such as:

   main.uacomment=bitcoin
   test.uacomment=bitcoin-testnet
   regtest.uacomment=regtest
   [main]
   mempoolsize=300
   [test]
   mempoolsize=100
   [regtest]
   mempoolsize=20

If the following options are not in a section, they will only apply to mainnet:
`addnode=`, `connect=`, `port=`, `bind=`, `rpcport=`, `rpcbind=` and `wallet=`.
The options to choose a network (`regtest=` and `testnet=`) must be specified
outside of sections.

'label' and 'account' APIs for wallet
-------------------------------------

A new 'label' API has been introduced for the wallet. This is intended as a
replacement for the deprecated 'account' API. The 'account' can continue to
be used in V0.17 by starting bitcoind with the '-deprecatedrpc=accounts'
argument, and will be fully removed in V0.18.

The label RPC methods mirror the account functionality, with the following functional differences:

- Labels can be set on any address, not just receiving addresses. This functionality was previously only available through the GUI.
- Labels can be deleted by reassigning all addresses using the `setlabel` RPC method.
- There isn't support for sending transactions _from_ a label, or for determining which label a transaction was sent from.
- Labels do not have a balance.

Here are the changes to RPC methods:

| Deprecated Method | New Method | Notes |
| :---------------------- | :-------------------- | :-----------|
| `getaccount` | `getaddressinfo` | `getaddressinfo` returns a json object with address information instead of just the name of the account as a string. |
| `getaccountaddress` | n/a | There is no replacement for `getaccountaddress` since labels do not have an associated receive address. |
| `getaddressesbyaccount` | `getaddressesbylabel` | `getaddressesbylabel` returns a json object with the addresses as keys, instead of a list of strings. |
| `getreceivedbyaccount` | `getreceivedbylabel` | _no change in behavior_ |
| `listaccounts` | `listlabels` | `listlabels` does not return a balance or accept `minconf` and `watchonly` arguments. |
| `listreceivedbyaccount` | `listreceivedbylabel` | Both methods return new `label` fields, along with `account` fields for backward compatibility. |
| `move` | n/a | _no replacement_ |
| `sendfrom` | n/a | _no replacement_ |
| `setaccount` | `setlabel` | Both methods now: <ul><li>allow assigning labels to any address, instead of raising an error if the address is not receiving address.<li>delete the previous label associated with an address when the final address using that label is reassigned to a different label, instead of making an implicit `getaccountaddress` call to ensure the previous label still has a receiving address. |

| Changed Method | Notes |
| :--------------------- | :------ |
| `addmultisigaddress` | Renamed `account` named parameter to `label`. Still accepts `account` for backward compatibility if running with '-deprecatedrpc=accounts'. |
| `getnewaddress` | Renamed `account` named parameter to `label`. Still accepts `account` for backward compatibility. if running with '-deprecatedrpc=accounts' |
| `listunspent` | Returns new `label` fields. `account` field will be returned for backward compatibility if running with '-deprecatedrpc=accounts' |
| `sendmany` | The `account` named parameter has been renamed to `dummy`. If provided, the `dummy` parameter must be set to the empty string, unless running with the `-deprecatedrpc=accounts` argument (in which case functionality is unchanged). |
| `listtransactions` | The `account` named parameter has been renamed to `dummy`. If provided, the `dummy` parameter must be set to the string `*`, unless running with the `-deprecatedrpc=accounts` argument (in which case functionality is unchanged). |
| `getbalance` | `account`, `minconf` and `include_watchonly` parameters are deprecated, and can only be used if running with '-deprecatedrpc=accounts' |

BIP 174 Partially Signed Bitcoin Transactions support
-----------------------------------------------------

[BIP 174 PSBT](https://github.com/bitcoin/bips/blob/master/bip-0174.mediawiki) is an interchange format for Bitcoin transactions that are not fully signed
yet, together with relevant metadata to help entities work towards signing it.
It is intended to simplify workflows where multiple parties need to cooperate to
produce a transaction. Examples include hardware wallets, multisig setups, and
[CoinJoin](https://bitcointalk.org/?topic=279249) transactions.

### Overall workflow

Overall, the construction of a fully signed Bitcoin transaction goes through the
following steps:

- A **Creator** proposes a particular transaction to be created. He constructs
  a PSBT that contains certain inputs and outputs, but no additional metadata.
- For each input, an **Updater** adds information about the UTXOs being spent by
  the transaction to the PSBT.
- A potentially other Updater adds information about the scripts and public keys
  involved in each of the inputs (and possibly outputs) of the PSBT.
- **Signers** inspect the transaction and its metadata to decide whether they
  agree with the transaction. They can use amount information from the UTXOs
  to assess the values and fees involved. If they agree, they produce a
  partial signature for the inputs for which they have relevant key(s).
- A **Finalizer** is run for each input to convert the partial signatures and
  possibly script information into a final `scriptSig` and/or `scriptWitness`.
- An **Extractor** produces a valid Bitcoin transaction (in network format)
  from a PSBT for which all inputs are finalized.

Generally, each of the above (excluding Creator and Extractor) will simply
add more and more data to a particular PSBT. In a naive workflow, they all have
to operate sequentially, passing the PSBT from one to the next, until the
Extractor can convert it to a real transaction. In order to permit parallel
operation, **Combiners** can be employed which merge metadata from different
PSBTs for the same unsigned transaction.

The names above in bold are the names of the roles defined in BIP174. They're
useful in understanding the underlying steps, but in practice, software and
hardware implementations will typically implement multiple roles simultaneously.

### RPCs

- **`converttopsbt` (Creator)** is a utility RPC that converts an
  unsigned raw transaction to PSBT format. It ignores existing signatures.
- **`createpsbt` (Creator)** is a utility RPC that takes a list of inputs and
  outputs and converts them to a PSBT with no additional information. It is
  equivalent to calling `createrawtransaction` followed by `converttopsbt`.
- **`walletcreatefundedpsbt` (Creator, Updater)** is a wallet RPC that creates a
  PSBT with the specified inputs and outputs, adds additional inputs and change
  to it to balance it out, and adds relevant metadata. In particular, for inputs
  that the wallet knows about (counting towards its normal or watch-only
  balance), UTXO information will be added. For outputs and inputs with UTXO
  information present, key and script information will be added which the wallet
  knows about. It is equivalent to running `createrawtransaction`, followed by
  `fundrawtransaction`, and `converttopsbt`.
- **`walletprocesspsbt` (Updater, Signer, Finalizer)** is a wallet RPC that takes as
  input a PSBT, adds UTXO, key, and script data to inputs and outputs that miss
  it, and optionally signs inputs. Where possible it also finalizes the partial
  signatures.
- **`finalizepsbt` (Finalizer, Extractor)** is a utility RPC that finalizes any
  partial signatures, and if all inputs are finalized, converts the result to a
  fully signed transaction which can be broadcast with `sendrawtransaction`.
- **`combinepsbt` (Combiner)** is a utility RPC that implements a Combiner. It
  can be used at any point in the workflow to merge information added to
  different versions of the same PSBT. In particular it is useful to combine the
  output of multiple Updaters or Signers.
- **`decodepsbt`** is a diagnostic utility RPC which will show all information in
  a PSBT in human-readable form, as well as compute its eventual fee if known.

Upgrading non-HD wallets to HD wallets
--------------------------------------

Since Bitcoin Core 0.13.0, creating new BIP 32 Hierarchical Deterministic wallets has been supported by Bitcoin Core but old non-HD wallets could not be upgraded to HD. Now non-HD wallets can be upgraded to HD using the `-upgradewallet` command line option. This upgrade will result in the all keys in the keypool being marked as used and a new keypool generated. **A new backup must be made when this upgrade is performed.**

Additionally, `-upgradewallet` can be used to upgraded from a non-split HD chain (all keys generated with `m/0'/0'/i'`) to a split HD chain (receiving keys generated with `'m/0'/0'/i'` and change keys generated with `m'/0'/1'/i'`). When this upgrade occurs, all keys already in the keypool will remain in the keypool to be used until all keys from before the upgrade are exhausted. This is to avoid issues with backups and downgrades when some keys may come from the change key keypool. Users can begin using the new split HD chain keypools by using the `newkeypool` RPC to mark all keys in the keypool as used and begin using a new keypool generated from the split HD chain.

HD Master key rotation
----------------------

A new RPC, `sethdseed`, has been introduced which allows users to set a new HD seed or set their own HD seed. This allows for a new HD seed to be used. **A new backup must be made when a new HD seed is set.**

Low-level RPC changes
---------------------

- The new RPC `scantxoutset` can be used to scan the UTXO set for entries
  that match certain output descriptors. Refer to the [output descriptors
  reference documentation](doc/descriptors.md) for more details. This call
  is similar to `listunspent` but does not use a wallet, meaning that the
  wallet can be disabled at compile or run time. This call is experimental,
  as such, is subject to changes or removal in future releases.

- The `createrawtransaction` RPC will now accept an array or dictionary (kept for compatibility) for the `outputs` parameter. This means the order of transaction outputs can be specified by the client.
- The `fundrawtransaction` RPC will reject the previously deprecated `reserveChangeKey` option.
- `sendmany` now shuffles outputs to improve privacy, so any previously expected behavior with regards to output ordering can no longer be relied upon.
- The new RPC `testmempoolaccept` can be used to test acceptance of a transaction to the mempool without adding it.
- JSON transaction decomposition now includes a `weight` field which provides
  the transaction's exact weight. This is included in REST /rest/tx/ and
  /rest/block/ endpoints when in json mode. This is also included in `getblock`
  (with verbosity=2), `listsinceblock`, `listtransactions`, and
  `getrawtransaction` RPC commands.
- New `fees` field introduced in `getrawmempool`, `getmempoolancestors`, `getmempooldescendants` and
   `getmempoolentry` when verbosity is set to `true` with sub-fields `ancestor`, `base`, `modified`
   and `descendant` denominated in BTC. This new field deprecates previous fee fields, such as
   `fee`, `modifiedfee`, `ancestorfee` and `descendantfee`.
- The new RPC `getzmqnotifications` returns information about active ZMQ
  notifications.
- When bitcoin is not started with any `-wallet=<path>` options, the name of
  the default wallet returned by `getwalletinfo` and `listwallets` RPCs is
  now the empty string `""` instead of `"wallet.dat"`. If bitcoin is started
  with any `-wallet=<path>` options, there is no change in behavior, and the
  name of any wallet is just its `<path>` string.
- Passing an empty string (`""`) as the `address_type` parameter to
  `getnewaddress`, `getrawchangeaddress`, `addmultisigaddress`,
  `fundrawtransaction` RPCs is now an error. Previously, this would fall back
  to using the default address type. It is still possible to pass null or leave
  the parameter unset to use the default address type.

- Bare multisig outputs to our keys are no longer automatically treated as
  incoming payments. As this feature was only available for multisig outputs for
  which you had all private keys in your wallet, there was generally no use for
  them compared to single-key schemes. Furthermore, no address format for such
  outputs is defined, and wallet software can't easily send to it. These outputs
  will no longer show up in `listtransactions`, `listunspent`, or contribute to
  your balance, unless they are explicitly watched (using `importaddress` or
  `importmulti` with hex script argument). `signrawtransaction*` also still
  works for them.

- The `getwalletinfo` RPC method now returns an `hdseedid` value, which is always the same as the incorrectly-named `hdmasterkeyid` value. `hdmasterkeyid` will be removed in V0.18.
- The `getaddressinfo` RPC method now returns an `hdseedid` value, which is always the same as the incorrectly-named `hdmasterkeyid` value. `hdmasterkeyid` will be removed in V0.18.

- Parts of the `validateaddress` RPC method have been deprecated and moved to
  `getaddressinfo`. Clients must transition to using `getaddressinfo` to access
  this information before upgrading to v0.18. The following deprecated fields
  have moved to `getaddressinfo` and will only be shown with
  `-deprecatedrpc=validateaddress`: `ismine`, `iswatchonly`, `script`, `hex`,
  `pubkeys`, `sigsrequired`, `pubkey`, `addresses`, `embedded`, `iscompressed`,
  `account`, `timestamp`, `hdkeypath`, `hdmasterkeyid`.
- `signrawtransaction` is deprecated and will be fully removed in v0.18. To use
  `signrawtransaction` in v0.17, restart bitcoind with
  `-deprecatedrpc=signrawtransaction`. Projects should transition to using
  `signrawtransactionwithkey` and `signrawtransactionwithwallet` before
  upgrading to v0.18.

Other API changes
-----------------

- The `inactivehdmaster` property in the `dumpwallet` output has been corrected to `inactivehdseed`

### Logging

- The log timestamp format is now ISO 8601 (e.g. "2018-02-28T12:34:56Z").

- When running bitcoind with `-debug` but without `-daemon`, logging to stdout
  is now the default behavior. Setting `-printtoconsole=1` no longer implicitly
  disables logging to debug.log. Instead, logging to file can be explicitly disabled
  by setting `-debuglogfile=0`.

Transaction index changes
-------------------------

The transaction index is now built separately from the main node procedure,
meaning the `-txindex` flag can be toggled without a full reindex. If bitcoind
is run with `-txindex` on a node that is already partially or fully synced
without one, the transaction index will be built in the background and become
available once caught up. When switching from running `-txindex` to running
without the flag, the transaction index database will *not* be deleted
automatically, meaning it could be turned back on at a later time without a full
resync.

Miner block size removed
------------------------

The `-blockmaxsize` option for miners to limit their blocks' sizes was
deprecated in V0.15.1, and has now been removed. Miners should use the
`-blockmaxweight` option if they want to limit the weight of their blocks.

Python Support
--------------

Support for Python 2 has been discontinued for all test files and tools.