12 files changed, 195 insertions, 116 deletions
diff --git a/doc/README.md b/doc/README.md
index 4dd21c4620..19d8204d83 100644
--- a/doc/README.md
+++ b/doc/README.md
@@ -30,7 +30,7 @@ Drag Bitcoin Core to your applications folder, and then run Bitcoin Core.
 
 * See the documentation at the [Bitcoin Wiki](https://en.bitcoin.it/wiki/Main_Page)
 for help and more information.
-* Ask for help on [#bitcoin](http://webchat.freenode.net?channels=bitcoin) on Freenode. If you don't have an IRC client, use [webchat here](http://webchat.freenode.net?channels=bitcoin).
+* Ask for help on [#bitcoin](https://webchat.freenode.net/#bitcoin) on Freenode. If you don't have an IRC client, use [webchat here](https://webchat.freenode.net/#bitcoin).
 * Ask for help on the [BitcoinTalk](https://bitcointalk.org/) forums, in the [Technical Support board](https://bitcointalk.org/index.php?board=4.0).
 
 Building
@@ -66,8 +66,8 @@ The Bitcoin repo's [root README](/README.md) contains relevant information on th
 
 ### Resources
 * Discuss on the [BitcoinTalk](https://bitcointalk.org/) forums, in the [Development & Technical Discussion board](https://bitcointalk.org/index.php?board=6.0).
-* Discuss project-specific development on #bitcoin-core-dev on Freenode. If you don't have an IRC client, use [webchat here](http://webchat.freenode.net/?channels=bitcoin-core-dev).
-* Discuss general Bitcoin development on #bitcoin-dev on Freenode. If you don't have an IRC client, use [webchat here](http://webchat.freenode.net/?channels=bitcoin-dev).
+* Discuss project-specific development on #bitcoin-core-dev on Freenode. If you don't have an IRC client, use [webchat here](https://webchat.freenode.net/#bitcoin-core-dev).
+* Discuss general Bitcoin development on #bitcoin-dev on Freenode. If you don't have an IRC client, use [webchat here](https://webchat.freenode.net/#bitcoin-dev).
 
 ### Miscellaneous
 - [Assets Attribution](assets-attribution.md)
diff --git a/doc/REST-interface.md b/doc/REST-interface.md
index a63391e01a..11e9c90f49 100644
--- a/doc/REST-interface.md
+++ b/doc/REST-interface.md
@@ -30,7 +30,7 @@ To query for a confirmed transaction, enable the transaction index via "txindex=
 Given a block hash: returns a block, in binary, hex-encoded binary or JSON formats.
 Responds with 404 if the block doesn't exist.
 
-The HTTP request and response are both handled entirely in-memory, thus making maximum memory usage at least 2.66MB (1 MB max block, plus hex encoding) per request.
+The HTTP request and response are both handled entirely in-memory.
 
 With the /notxdetails/ option JSON response will only contain the transaction hash instead of the complete transaction details. The option only affects the JSON response.
 
diff --git a/doc/dependencies.md b/doc/dependencies.md
index 51a2240107..0cb5311e8b 100644
--- a/doc/dependencies.md
+++ b/doc/dependencies.md
@@ -13,7 +13,7 @@ These are the dependencies currently used by Bitcoin Core. You can find instruct
 | FreeType | [2.7.1](https://download.savannah.gnu.org/releases/freetype) |  | No |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) (Android only) |
 | GCC |  | [4.8+](https://gcc.gnu.org/) (C++11 support) |  |  |  |
 | HarfBuzz-NG |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) |
-| libevent | [2.1.11-stable](https://github.com/libevent/libevent/releases) | 2.0.22 | No |  |  |
+| libevent | [2.1.11-stable](https://github.com/libevent/libevent/releases) | [2.0.21](https://github.com/bitcoin/bitcoin/pull/18676) | No |  |  |
 | libpng |  |  |  |  | [Yes](https://github.com/bitcoin/bitcoin/blob/master/depends/packages/qt.mk) |
 | librsvg | |  |  |  |  |
 | MiniUPnPc | [2.0.20180203](https://miniupnp.tuxfamily.org/files) |  | No |  |  |
diff --git a/doc/developer-notes.md b/doc/developer-notes.md
index da07080724..b33b3ad18a 100644
--- a/doc/developer-notes.md
+++ b/doc/developer-notes.md
@@ -423,27 +423,52 @@ and its `cs_KeyStore` lock for example).
 Threads
 -------
 
-- ThreadScriptCheck : Verifies block scripts.
+- [Main thread (`bitcoind`)](https://doxygen.bitcoincore.org/bitcoind_8cpp.html#a0ddf1224851353fc92bfbff6f499fa97)
+  : Started from `main()` in `bitcoind.cpp`. Responsible for starting up and
+  shutting down the application.
 
-- ThreadImport : Loads blocks from `blk*.dat` files or `-loadblock=<file>`.
+- [ThreadImport (`b-loadblk`)](https://doxygen.bitcoincore.org/init_8cpp.html#ae9e290a0e829ec0198518de2eda579d1)
+  : Loads blocks from `blk*.dat` files or `-loadblock=<file>` on startup.
 
-- ThreadDNSAddressSeed : Loads addresses of peers from the DNS.
+- [ThreadScriptCheck (`b-scriptch.x`)](https://doxygen.bitcoincore.org/validation_8cpp.html#a925a33e7952a157922b0bbb8dab29a20)
+  : Parallel script validation threads for transactions in blocks.
 
-- ThreadMapPort : Universal plug-and-play startup/shutdown.
+- [ThreadHTTP (`b-http`)](https://doxygen.bitcoincore.org/httpserver_8cpp.html#abb9f6ea8819672bd9a62d3695070709c)
+  : Libevent thread to listen for RPC and REST connections.
 
-- ThreadSocketHandler : Sends/Receives data from peers on port 8333.
+- [HTTP worker threads(`b-httpworker.x`)](https://doxygen.bitcoincore.org/httpserver_8cpp.html#aa6a7bc27265043bc0193220c5ae3a55f)
+  : Threads to service RPC and REST requests.
 
-- ThreadOpenAddedConnections : Opens network connections to added nodes.
+- [Indexer threads (`b-txindex`, etc)](https://doxygen.bitcoincore.org/class_base_index.html#a96a7407421fbf877509248bbe64f8d87)
+  : One thread per indexer.
 
-- ThreadOpenConnections : Initiates new connections to peers.
+- [SchedulerThread (`b-scheduler`)](https://doxygen.bitcoincore.org/class_c_scheduler.html#a14d2800815da93577858ea078aed1fba)
+  : Does asynchronous background tasks like dumping wallet contents, dumping
+  addrman and running asynchronous validationinterface callbacks.
 
-- ThreadMessageHandler : Higher-level message handling (sending and receiving).
+- [TorControlThread (`b-torcontrol`)](https://doxygen.bitcoincore.org/torcontrol_8cpp.html#a4faed3692d57a0d7bdbecf3b37f72de0)
+  : Libevent thread for tor connections.
 
-- DumpAddresses : Dumps IP addresses of nodes to `peers.dat`.
+- Net threads:
 
-- ThreadRPCServer : Remote procedure call handler, listens on port 8332 for connections and services them.
+  - [ThreadMessageHandler (`b-msghand`)](https://doxygen.bitcoincore.org/class_c_connman.html#aacdbb7148575a31bb33bc345e2bf22a9)
+    : Application level message handling (sending and receiving). Almost
+    all net_processing and validation logic runs on this thread.
 
-- Shutdown : Does an orderly shutdown of everything.
+  - [ThreadDNSAddressSeed (`b-dnsseed`)](https://doxygen.bitcoincore.org/class_c_connman.html#aa7c6970ed98a4a7bafbc071d24897d13)
+    : Loads addresses of peers from the DNS.
+
+  - [ThreadMapPort (`b-upnp`)](https://doxygen.bitcoincore.org/net_8cpp.html#a63f82a71c4169290c2db1651a9bbe249)
+    : Universal plug-and-play startup/shutdown.
+
+  - [ThreadSocketHandler (`b-net`)](https://doxygen.bitcoincore.org/class_c_connman.html#a765597cbfe99c083d8fa3d61bb464e34)
+    : Sends/Receives data from peers on port 8333.
+
+  - [ThreadOpenAddedConnections (`b-addcon`)](https://doxygen.bitcoincore.org/class_c_connman.html#a0b787caf95e52a346a2b31a580d60a62)
+    : Opens network connections to added nodes.
+
+  - [ThreadOpenConnections (`b-opencon`)](https://doxygen.bitcoincore.org/class_c_connman.html#a55e9feafc3bab78e5c9d408c207faa45)
+    : Initiates new connections to peers.
 
 Ignoring IDE/editor files
 --------------------------
@@ -965,7 +990,7 @@ Some good examples of scripted-diff:
 - [scripted-diff: Rename InitInterfaces to NodeContext](https://github.com/bitcoin/bitcoin/commit/301bd41a2e6765b185bd55f4c541f9e27aeea29d)
 uses an elegant script to replace occurrences of multiple terms in all source files.
 
-- [scripted-diff: Remove g_connman, g_banman globals](https://github.com/bitcoin/bitcoin/commit/301bd41a2e6765b185bd55f4c541f9e27aeea29d)
+- [scripted-diff: Remove g_connman, g_banman globals](https://github.com/bitcoin/bitcoin/commit/8922d7f6b751a3e6b3b9f6fb7961c442877fb65a)
 replaces specific terms in a list of specific source files.
 
 - [scripted-diff: Replace fprintf with tfm::format](https://github.com/bitcoin/bitcoin/commit/fac03ec43a15ad547161e37e53ea82482cc508f9)
diff --git a/doc/fuzzing.md b/doc/fuzzing.md
index 9642337821..419b1db44e 100644
--- a/doc/fuzzing.md
+++ b/doc/fuzzing.md
@@ -133,3 +133,25 @@ $ afl/afl-fuzz -i inputs/ -o outputs/ -- src/test/fuzz/bech32
 ```
 
 Read the [`afl-fuzz` documentation](https://github.com/google/afl) for more information.
+
+# Fuzzing Bitcoin Core using Honggfuzz
+
+## Quickstart guide
+
+To quickly get started fuzzing Bitcoin Core using [Honggfuzz](https://github.com/google/honggfuzz):
+
+```sh
+$ git clone https://github.com/bitcoin/bitcoin
+$ cd bitcoin/
+$ ./autogen.sh
+$ git clone https://github.com/google/honggfuzz
+$ cd honggfuzz/
+$ make
+$ cd ..
+$ CC=$(pwd)/honggfuzz/hfuzz_cc/hfuzz-clang CXX=$(pwd)/honggfuzz/hfuzz_cc/hfuzz-clang++ ./configure --enable-fuzz --with-sanitizers=address,undefined
+$ make
+$ mkdir -p inputs/
+$ honggfuzz/honggfuzz -i inputs/ -- src/test/fuzz/process_message
+```
+
+Read the [Honggfuzz documentation](https://github.com/google/honggfuzz/blob/master/docs/USAGE.md) for more information.
diff --git a/doc/init.md b/doc/init.md
index 0b327aab58..99aa0a0def 100644
--- a/doc/init.md
+++ b/doc/init.md
@@ -20,9 +20,9 @@ The macOS configuration assumes bitcoind will be set up for the current user.
 Configuration
 ---------------------------------
 
-At a bare minimum, bitcoind requires that the rpcpassword setting be set
-when running as a daemon.  If the configuration file does not exist or this
-setting is not set, bitcoind will shut down promptly after startup.
+Running bitcoind as a daemon does not require any manual configuration. You may
+set the `rpcauth` setting in the `bitcoin.conf` configuration file to override
+the default behaviour of using a special cookie for authentication.
 
 This password does not have to be remembered or typed as it is mostly used
 as a fixed token that bitcoind and client programs read from the configuration
diff --git a/doc/productivity.md b/doc/productivity.md
index b25ddc94e5..1bf3d9afb5 100644
--- a/doc/productivity.md
+++ b/doc/productivity.md
@@ -172,11 +172,11 @@ When looking at other's pull requests, it may make sense to add the following se
 
 ```
 [remote "upstream-pull"]
-        fetch = +refs/pull/*:refs/remotes/upstream-pull/*
+        fetch = +refs/pull/*/head:refs/remotes/upstream-pull/*
         url = git@github.com:bitcoin/bitcoin.git
 ```
 
-This will add an `upstream-pull` remote to your git repository, which can be fetched using `git fetch --all` or `git fetch upstream-pull`. Afterwards, you can use `upstream-pull/NUMBER/head` in arguments to `git show`, `git checkout` and anywhere a commit id would be acceptable to see the changes from pull request NUMBER.
+This will add an `upstream-pull` remote to your git repository, which can be fetched using `git fetch --all` or `git fetch upstream-pull`. It will download and store on disk quite a lot of data (all PRs, including merged and closed ones). Afterwards, you can use `upstream-pull/NUMBER/head` in arguments to `git show`, `git checkout` and anywhere a commit id would be acceptable to see the changes from pull request NUMBER.
 
 ### Diff the diffs with `git range-diff`
 
diff --git a/doc/rapidcheck.md b/doc/rapidcheck.md
deleted file mode 100644
index 397a907f17..0000000000
--- a/doc/rapidcheck.md
+++ /dev/null
@@ -1,84 +0,0 @@
-# RapidCheck property-based testing for Bitcoin Core
-
-## Concept
-
-Property-based testing is experimentally being added to Bitcoin Core with
-[RapidCheck](https://github.com/emil-e/rapidcheck), a C++ framework for
-property-based testing inspired by the Haskell library
-[QuickCheck](https://hackage.haskell.org/package/QuickCheck).
-
-RapidCheck performs random testing of program properties. A specification of the
-program is given in the form of properties which functions should satisfy, and
-RapidCheck tests that the properties hold in a large number of randomly
-generated cases.
-
-If an exception is found, RapidCheck tries to find the smallest case, for some
-definition of smallest, for which the property is still false and displays it as
-a counter-example. For example, if the input is an integer, RapidCheck tries to
-find the smallest integer for which the property is false.
-
-## Running
-
-If RapidCheck is installed, Bitcoin Core will automatically run the
-property-based tests with the unit tests during `make check`, unless the
-`--without-rapidcheck` flag is passed when configuring.
-
-For more information, run `./configure --help` and see `--with-rapidcheck` under
-Optional Packages.
-
-## Setup
-
-The following instructions have been tested with Linux Debian and macOS.
-
-1. Clone the RapidCheck source code and cd into the repository.
-
-    ```shell
-    git clone https://github.com/emil-e/rapidcheck.git
-    cd rapidcheck
-    ```
-
-2. Build RapidCheck (requires CMake to be installed).
-
-    ```shell
-    cmake -DCMAKE_POSITION_INDEPENDENT_CODE:BOOL=true -DRC_ENABLE_BOOST_TEST=ON $(pwd)
-    make && make install
-    ```
-
-3. Configure Bitcoin Core with RapidCheck.
-
-    `cd` to the directory of your local bitcoin repository and run
-    `./configure`. In the output you should see:
-
-    ```shell
-    checking rapidcheck.h usability... yes
-    checking rapidcheck.h presence... yes
-    checking for rapidcheck.h... yes
-    [...]
-    Options used to compile and link:
-    [...]
-      with test     = yes
-        with prop   = yes
-    ```
-
-4. Build Bitcoin Core with RapidCheck.
-
-    Now you can run `make` and should see the property-based tests compiled with
-    the unit tests:
-
-    ```shell
-    Making all in src
-    [...]
-    CXX      test/gen/test_bitcoin-crypto_gen.o
-    CXX      test/test_bitcoin-key_properties.o
-    ```
-
-5. Run the unit tests with `make check`. The property-based tests will be run
-   with the unit tests.
-
-    ```shell
-    Running tests: crypto_tests from test/crypto_tests.cpp
-    [...]
-    Running tests: key_properties from test/key_properties.cpp
-    ```
-
-That's it! You are now running property-based tests in Bitcoin Core.
diff --git a/doc/reduce-memory.md b/doc/reduce-memory.md
index b0faf0825a..6e7a578ecc 100644
--- a/doc/reduce-memory.md
+++ b/doc/reduce-memory.md
@@ -24,8 +24,9 @@ The size of some in-memory caches can be reduced. As caches trade off memory usa
 
 ## Number of peers
 
-- `-maxconnections=<n>` - the maximum number of connections, this defaults to `125`. Each active connection takes up some memory. Only significant if incoming
-   connections are enabled, otherwise the number of connections will never be more than `8`.
+- `-maxconnections=<n>` - the maximum number of connections, this defaults to 125. Each active connection takes up some
+  memory. This option applies only if incoming connections are enabled, otherwise the number of connections will never
+  be more than 10. Of the 10 outbound peers, there can be 8 full-relay connections and 2 block-relay-only ones.
 
 ## Thread configuration
 
diff --git a/doc/reduce-traffic.md b/doc/reduce-traffic.md
index 5a71f62e0f..e39e43df7a 100644
--- a/doc/reduce-traffic.md
+++ b/doc/reduce-traffic.md
@@ -3,8 +3,10 @@ Reduce Traffic
 
 Some node operators need to deal with bandwidth caps imposed by their ISPs.
 
-By default, Bitcoin Core allows up to 125 connections to different peers, 8 of
-which are outbound. You can therefore, have at most 117 inbound connections.
+By default, Bitcoin Core allows up to 125 connections to different peers, 10 of
+which are outbound. You can therefore, have at most 115 inbound connections.
+Of the 10 outbound peers, there can be 8 full-relay connections and 2
+block-relay-only ones.
 
 The default settings can result in relatively significant traffic consumption.
 
@@ -26,7 +28,7 @@ calculating the target.
 
 ## 2. Disable "listening" (`-listen=0`)
 
-Disabling listening will result in fewer nodes connected (remember the maximum of 8
+Disabling listening will result in fewer nodes connected (remember the maximum of 10
 outbound peers). Fewer nodes will result in less traffic usage as you are relaying
 blocks and transactions to fewer nodes.
 
@@ -44,7 +46,11 @@ with other peers, you can disable transaction relay.
 Be reminded of the effects of this setting.
 
 - Fee estimation will no longer work.
-- Not relaying other's transactions could hurt your privacy if used while a
-  wallet is loaded or if you use the node to broadcast transactions.
+- It sets the flag "-walletbroadcast" to be "0", only if it is currently unset.
+  Doing so disables the automatic broadcasting of transactions from wallet. Not
+  relaying other's transactions could hurt your privacy if used while a wallet
+  is loaded or if you use the node to broadcast transactions.
+- If a peer is whitelisted and "-whitelistforcerelay" is set to "1" (which will
+  also set "whitelistrelay" to "1"), we will still receive and relay their transactions.
 - It makes block propagation slower because compact block relay can only be
   used when transaction relay is enabled.
diff --git a/doc/release-notes.md b/doc/release-notes.md
index cd6a4d6b59..0d668a6302 100644
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -1,5 +1,114 @@
-Please edit the release notes here:
+*After branching off for a major version release of Bitcoin Core, use this
+template to create the initial release notes draft.*
 
-https://github.com/bitcoin-core/bitcoin-devwiki/wiki/0.20.0-Release-Notes-Draft
+*The release notes draft is a temporary file that can be added to by anyone. See
+[/doc/developer-notes.md#release-notes](/doc/developer-notes.md#release-notes)
+for the process.*
+
+*Create the draft, named* "*version* Release Notes Draft"
+*(e.g. "0.20.0 Release Notes Draft"), as a collaborative wiki in:*
+
+https://github.com/bitcoin-core/bitcoin-devwiki/wiki/
 
 *Before the final release, move the notes back to this git repository.*
+
+*version* Release Notes Draft
+===============================
+
+Bitcoin Core version *version* is now available from:
+
+  <https://bitcoincore.org/bin/bitcoin-core-*version*/>
+
+This release includes new features, various bug fixes and performance
+improvements, as well as updated translations.
+
+Please report bugs using the issue tracker at GitHub:
+
+  <https://github.com/bitcoin/bitcoin/issues>
+
+To receive security and update notifications, please subscribe to:
+
+  <https://bitcoincore.org/en/list/announcements/join/>
+
+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).
+
+Upgrading directly from a version of Bitcoin Core that has reached its EOL is
+possible, but it might take some time if the datadir needs to be migrated. Old
+wallet versions of Bitcoin Core are generally supported.
+
+Compatibility
+==============
+
+Bitcoin Core is supported and extensively tested on operating systems using
+the Linux kernel, macOS 10.12+, and Windows 7 and newer. It is not recommended
+to use Bitcoin Core on unsupported systems.
+
+Bitcoin Core should also work on most other Unix-like systems but is not
+as frequently tested on them.
+
+From Bitcoin Core 0.20.0 onwards, macOS versions earlier than 10.12 are no
+longer supported. Additionally, Bitcoin Core does not yet change appearance
+when macOS "dark mode" is activated.
+
+In addition to previously supported CPU platforms, this release's pre-compiled
+distribution provides binaries for the RISC-V platform.
+
+Notable changes
+===============
+
+P2P and network changes
+-----------------------
+
+Updated RPCs
+------------
+
+Changes to Wallet or GUI related RPCs can be found in the GUI or Wallet section below.
+
+New RPCs
+--------
+
+Build System
+------------
+
+Updated settings
+----------------
+
+Changes to Wallet or GUI related settings can be found in the GUI or Wallet  section below.
+
+New settings
+------------
+
+Wallet
+------
+
+#### Wallet RPC changes
+
+- The `upgradewallet` RPC replaces the `-upgradewallet` command line option.
+  (#15761)
+- The `settxfee` RPC will fail if the fee was set higher than the `-maxtxfee`
+  command line setting. The wallet will already fail to create transactions
+  with fees higher than `-maxtxfee`. (#18467)
+
+GUI changes
+-----------
+
+Low-level changes
+=================
+
+Tests
+-----
+
+Credits
+=======
+
+Thanks to everyone who directly contributed to this release:
+
+
+As well as to everyone that helped with translations on
+[Transifex](https://www.transifex.com/bitcoin/bitcoin/).
diff --git a/doc/release-process.md b/doc/release-process.md
index e0f29f6ad7..a61b67c35f 100644
--- a/doc/release-process.md
+++ b/doc/release-process.md
@@ -219,7 +219,7 @@ Codesigner only: Commit the detached codesign payloads:
     rm -rf *
     tar xf signature-osx.tar.gz
     tar xf signature-win.tar.gz
-    git add -a
+    git add -A
     git commit -m "point to ${VERSION}"
     git tag -s v${VERSION} HEAD
     git push the current branch and new tag