diff --git a/doc/release-notes.md b/doc/release-notes.md
index 5346a4a3e..3aea2774c 100644
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -1,24 +1,24 @@
 # Bitcoin ABC 0.23.0 Release Notes
 
 Bitcoin ABC version 0.23.0 is now available from:
 
   <https://download.bitcoinabc.org/0.23.0/>
 
 This release includes the following features and fixes:
  - The node's known peers are persisted to disk in a file called `peers.dat`. The
    format of this file has been changed in a backwards-incompatible way in order to
    accommodate the storage of Tor v3 and other BIP155 addresses. This means that if
    the file is modified by 0.23.0 or newer then older versions will not be able to
    read it. Those old versions, in the event of a downgrade, will log an error
-   message that deserialization has failed and will continue normal operation
-   as if the file was missing, creating a new empty one.
+   message "Incorrect keysize in addrman deserialization" and will continue normal
+   operation as if the file was missing, creating a new empty one.
  - The Tor onion service that is automatically created by setting the
    `-listenonion` configuration parameter will now be created as a Tor v3 service
    instead of Tor v2. The private key that was used for Tor v2 (if any) will be
    left untouched in the `onion_private_key` file in the data directory (see
    `-datadir`) and can be removed if not needed. Bitcoin ABC will no longer
    attempt to read it. The private key for the Tor v3 service will be saved in a
    file named `onion_v3_private_key`. To use the deprecated Tor v2 service (not
    recommended), then `onion_private_key` can be copied over
    `onion_v3_private_key`, e.g.
    `cp -f onion_private_key onion_v3_private_key`.
diff --git a/src/addrman.h b/src/addrman.h
index 7e7d0db6f..8011f9897 100644
--- a/src/addrman.h
+++ b/src/addrman.h
@@ -1,751 +1,776 @@
 // Copyright (c) 2012 Pieter Wuille
 // Copyright (c) 2012-2016 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #ifndef BITCOIN_ADDRMAN_H
 #define BITCOIN_ADDRMAN_H
 
 #include <clientversion.h>
+#include <config/bitcoin-config.h>
 #include <fs.h>
 #include <hash.h>
 #include <netaddress.h>
 #include <protocol.h>
 #include <random.h>
 #include <streams.h>
 #include <sync.h>
 #include <timedata.h>
 #include <util/system.h>
 
 #include <tinyformat.h>
 
 #include <cstdint>
 #include <iostream>
 #include <map>
 #include <set>
 #include <vector>
 
 /**
  * Extended statistics about a CAddress
  */
 class CAddrInfo : public CAddress {
 public:
     //! last try whatsoever by us (memory only)
     int64_t nLastTry{0};
 
     //! last counted attempt (memory only)
     int64_t nLastCountAttempt{0};
 
 private:
     //! where knowledge about this address first came from
     CNetAddr source;
 
     //! last successful connection by us
     int64_t nLastSuccess{0};
 
     //! connection attempts since last successful attempt
     int nAttempts{0};
 
     //! reference count in new sets (memory only)
     int nRefCount{0};
 
     //! in tried set? (memory only)
     bool fInTried{false};
 
     //! position in vRandom
     int nRandomPos{-1};
 
     friend class CAddrMan;
 
 public:
     SERIALIZE_METHODS(CAddrInfo, obj) {
         READWRITEAS(CAddress, obj);
         READWRITE(obj.source, obj.nLastSuccess, obj.nAttempts);
     }
 
     CAddrInfo(const CAddress &addrIn, const CNetAddr &addrSource)
         : CAddress(addrIn), source(addrSource) {}
 
     CAddrInfo() : CAddress(), source() {}
 
     //! Calculate in which "tried" bucket this entry belongs
     int GetTriedBucket(const uint256 &nKey,
                        const std::vector<bool> &asmap) const;
 
     //! Calculate in which "new" bucket this entry belongs, given a certain
     //! source
     int GetNewBucket(const uint256 &nKey, const CNetAddr &src,
                      const std::vector<bool> &asmap) const;
 
     //! Calculate in which "new" bucket this entry belongs, using its default
     //! source
     int GetNewBucket(const uint256 &nKey,
                      const std::vector<bool> &asmap) const {
         return GetNewBucket(nKey, source, asmap);
     }
 
     //! Calculate in which position of a bucket to store this entry.
     int GetBucketPosition(const uint256 &nKey, bool fNew, int nBucket) const;
 
     //! Determine whether the statistics about this entry are bad enough so that
     //! it can just be deleted
     bool IsTerrible(int64_t nNow = GetAdjustedTime()) const;
 
     //! Calculate the relative chance this entry should be given when selecting
     //! nodes to connect to
     double GetChance(int64_t nNow = GetAdjustedTime()) const;
 };
 
 /** Stochastic address manager
  *
  * Design goals:
  *  * Keep the address tables in-memory, and asynchronously dump the entire
  * table to peers.dat.
  *  * Make sure no (localized) attacker can fill the entire table with his
  * nodes/addresses.
  *
  * To that end:
  *  * Addresses are organized into buckets.
  *    * Addresses that have not yet been tried go into 1024 "new" buckets.
  *      * Based on the address range (/16 for IPv4) of the source of
  * information, 64 buckets are selected at random.
  *      * The actual bucket is chosen from one of these, based on the range in
  * which the address itself is located.
  *      * One single address can occur in up to 8 different buckets to increase
  * selection chances for addresses that
  *        are seen frequently. The chance for increasing this multiplicity
  * decreases exponentially.
  *      * When adding a new address to a full bucket, a randomly chosen entry
  * (with a bias favoring less recently seen
  *        ones) is removed from it first.
  *    * Addresses of nodes that are known to be accessible go into 256 "tried"
  * buckets.
  *      * Each address range selects at random 8 of these buckets.
  *      * The actual bucket is chosen from one of these, based on the full
  * address.
  *      * When adding a new good address to a full bucket, a randomly chosen
  * entry (with a bias favoring less recently
  *        tried ones) is evicted from it, back to the "new" buckets.
  *    * Bucket selection is based on cryptographic hashing, using a
  * randomly-generated 256-bit key, which should not
  *      be observable by adversaries.
  *    * Several indexes are kept for high performance. Defining DEBUG_ADDRMAN
  * will introduce frequent (and expensive)
  *      consistency checks for the entire data structure.
  */
 
 //! total number of buckets for tried addresses
 #define ADDRMAN_TRIED_BUCKET_COUNT_LOG2 8
 
 //! total number of buckets for new addresses
 #define ADDRMAN_NEW_BUCKET_COUNT_LOG2 10
 
 //! maximum allowed number of entries in buckets for new and tried addresses
 #define ADDRMAN_BUCKET_SIZE_LOG2 6
 
 //! over how many buckets entries with tried addresses from a single group (/16
 //! for IPv4) are spread
 #define ADDRMAN_TRIED_BUCKETS_PER_GROUP 8
 
 //! over how many buckets entries with new addresses originating from a single
 //! group are spread
 #define ADDRMAN_NEW_BUCKETS_PER_SOURCE_GROUP 64
 
 //! in how many buckets for entries with new addresses a single address may
 //! occur
 #define ADDRMAN_NEW_BUCKETS_PER_ADDRESS 8
 
 //! how old addresses can maximally be
 #define ADDRMAN_HORIZON_DAYS 30
 
 //! after how many failed attempts we give up on a new node
 #define ADDRMAN_RETRIES 3
 
 //! how many successive failures are allowed ...
 #define ADDRMAN_MAX_FAILURES 10
 
 //! ... in at least this many days
 #define ADDRMAN_MIN_FAIL_DAYS 7
 
 //! how recent a successful connection should be before we allow an address to
 //! be evicted from tried
 #define ADDRMAN_REPLACEMENT_SECONDS (4 * 60 * 60)
 
 //! the maximum percentage of nodes to return in a getaddr call
 #define ADDRMAN_GETADDR_MAX_PCT 23
 
 //! the maximum number of nodes to return in a getaddr call
 #define ADDRMAN_GETADDR_MAX 2500
 
 //! Convenience
 #define ADDRMAN_TRIED_BUCKET_COUNT (1 << ADDRMAN_TRIED_BUCKET_COUNT_LOG2)
 #define ADDRMAN_NEW_BUCKET_COUNT (1 << ADDRMAN_NEW_BUCKET_COUNT_LOG2)
 #define ADDRMAN_BUCKET_SIZE (1 << ADDRMAN_BUCKET_SIZE_LOG2)
 
 //! the maximum number of tried addr collisions to store
 #define ADDRMAN_SET_TRIED_COLLISION_SIZE 10
 
 //! the maximum time we'll spend trying to resolve a tried table collision, in
 //! seconds (40 minutes)
 static const int64_t ADDRMAN_TEST_WINDOW = 40 * 60;
 
 /**
  * Stochastical (IP) address manager
  */
 class CAddrMan {
     friend class CAddrManTest;
 
 protected:
     //! critical section to protect the inner data structures
     mutable RecursiveMutex cs;
 
 private:
+    //! Serialization versions.
+    enum Format : uint8_t {
+        //! historic format, before commit e6b343d88
+        V0_HISTORICAL = 0,
+        //! for pre-asmap files
+        V1_DETERMINISTIC = 1,
+        //! for files including asmap version
+        V2_ASMAP = 2,
+        //! same as V2_ASMAP plus addresses are in BIP155 format
+        V3_BIP155 = 3,
+    };
+
+    //! The maximum format this software knows it can unserialize. Also, we
+    //! always serialize in this format. The format (first byte in the
+    //! serialized stream) can be higher than this and still this software may
+    //! be able to unserialize the file - if the second byte (see
+    //! `lowest_compatible` in `Unserialize()`) is less or equal to this.
+    static constexpr Format FILE_FORMAT = Format::V3_BIP155;
+
+    //! The initial value of a field that is incremented every time an
+    //! incompatible format change is made (such that old software versions
+    //! would not be able to parse and understand the new file format). This is
+    //! 32 because we overtook the "key size" field which was 32 historically.
+    //! @note Don't increment this. Increment `lowest_compatible` in
+    //! `Serialize()` instead.
+    static constexpr uint8_t INCOMPATIBILITY_BASE = 32;
+
     //! last used nId
     int nIdCount GUARDED_BY(cs);
 
     //! table with information about all nIds
     std::map<int, CAddrInfo> mapInfo GUARDED_BY(cs);
 
     //! find an nId based on its network address
     std::map<CNetAddr, int> mapAddr GUARDED_BY(cs);
 
     //! randomly-ordered vector of all nIds
     std::vector<int> vRandom GUARDED_BY(cs);
 
     // number of "tried" entries
     int nTried GUARDED_BY(cs);
 
     //! list of "tried" buckets
     int vvTried[ADDRMAN_TRIED_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);
 
     //! number of (unique) "new" entries
     int nNew GUARDED_BY(cs);
 
     //! list of "new" buckets
     int vvNew[ADDRMAN_NEW_BUCKET_COUNT][ADDRMAN_BUCKET_SIZE] GUARDED_BY(cs);
 
     //! last time Good was called (memory only)
     int64_t nLastGood GUARDED_BY(cs);
 
     //! Holds addrs inserted into tried table that collide with existing
     //! entries. Test-before-evict discipline used to resolve these collisions.
     std::set<int> m_tried_collisions;
 
 protected:
     //! secret key to randomize bucket select with
     uint256 nKey;
 
     //! Source of random numbers for randomization in inner loops
     FastRandomContext insecure_rand;
 
     //! Find an entry.
     CAddrInfo *Find(const CNetAddr &addr, int *pnId = nullptr)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! find an entry, creating it if necessary.
     //! nTime and nServices of the found node are updated, if necessary.
     CAddrInfo *Create(const CAddress &addr, const CNetAddr &addrSource,
                       int *pnId = nullptr) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Swap two elements in vRandom.
     void SwapRandom(unsigned int nRandomPos1, unsigned int nRandomPos2)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Move an entry from the "new" table(s) to the "tried" table
     void MakeTried(CAddrInfo &info, int nId) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Delete an entry. It must not be in tried, and have refcount 0.
     void Delete(int nId) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Clear a position in a "new" table. This is the only place where entries
     //! are actually deleted.
     void ClearNew(int nUBucket, int nUBucketPos) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Mark an entry "good", possibly moving it from "new" to "tried".
     void Good_(const CService &addr, bool test_before_evict, int64_t time)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Add an entry to the "new" table.
     bool Add_(const CAddress &addr, const CNetAddr &source,
               int64_t nTimePenalty) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Mark an entry as attempted to connect.
     void Attempt_(const CService &addr, bool fCountFailure, int64_t nTime)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Select an address to connect to, if newOnly is set to true, only the new
     //! table is selected from.
     CAddrInfo Select_(bool newOnly) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! See if any to-be-evicted tried table entries have been tested and if so
     //! resolve the collisions.
     void ResolveCollisions_() EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Return a random to-be-evicted tried table address.
     CAddrInfo SelectTriedCollision_() EXCLUSIVE_LOCKS_REQUIRED(cs);
 
 #ifdef DEBUG_ADDRMAN
     //! Perform consistency check. Returns an error code or zero.
     int Check_() EXCLUSIVE_LOCKS_REQUIRED(cs);
 #endif
 
     //! Select several addresses at once.
     void GetAddr_(std::vector<CAddress> &vAddr) EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Mark an entry as currently-connected-to.
     void Connected_(const CService &addr, int64_t nTime)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
     //! Update an entry's service bits.
     void SetServices_(const CService &addr, ServiceFlags nServices)
         EXCLUSIVE_LOCKS_REQUIRED(cs);
 
 public:
-    //! Serialization versions.
-    enum class Format : uint8_t {
-        //! historic format, before commit e6b343d88
-        V0_HISTORICAL = 0,
-        //! for pre-asmap files
-        V1_DETERMINISTIC = 1,
-        //! for files including asmap version
-        V2_ASMAP = 2,
-        //! same as V2_ASMAP plus addresses are in BIP155 format
-        V3_BIP155 = 3,
-    };
-
     // Compressed IP->ASN mapping, loaded from a file when a node starts.
     // Should be always empty if no file was provided.
     // This mapping is then used for bucketing nodes in Addrman.
     //
     // If asmap is provided, nodes will be bucketed by
     // AS they belong to, in order to make impossible for a node
     // to connect to several nodes hosted in a single AS.
     // This is done in response to Erebus attack, but also to generally
     // diversify the connections every node creates,
     // especially useful when a large fraction of nodes
     // operate under a couple of cloud providers.
     //
     // If a new asmap was provided, the existing records
     // would be re-bucketed accordingly.
     std::vector<bool> m_asmap;
 
     // Read asmap from provided binary file
     static std::vector<bool> DecodeAsmap(fs::path path);
 
     /**
      * Serialized format.
-     * * version byte (@see `Format`)
-     * * 0x20 + nKey (serialized as if it were a vector, for backward
-     * compatibility)
+     * * format version byte (@see `Format`)
+     * * lowest compatible format version byte. This is used to help old
+     * software decide whether to parse the file. For example:
+     *   * Bitcoin ABC version N knows how to parse up to format=3. If a new
+     * format=4 is introduced in version N+1 that is compatible with format=3
+     * and it is known that version N will be able to parse it, then version N+1
+     * will write (format=4, lowest_compatible=3) in the first two bytes of the
+     * file, and so version N will still try to parse it.
+     *   * Bitcoin ABC version N+2 introduces a new incompatible format=5. It
+     * will write (format=5, lowest_compatible=5) and so any versions that do
+     * not know how to parse format=5 will not try to read the file.
+     * * nKey
      * * nNew
      * * nTried
      * * number of "new" buckets XOR 2**30
      * * all nNew addrinfos in vvNew
      * * all nTried addrinfos in vvTried
      * * for each bucket:
      *   * number of elements
      *   * for each element: index
      *
      * 2**30 is xorred with the number of buckets to make addrman deserializer
      * v0 detect it as incompatible. This is necessary because it did not check
      * the version number on deserialization.
      *
      * Notice that vvTried, mapAddr and vVector are never encoded explicitly;
      * they are instead reconstructed from the other information.
      *
      * vvNew is serialized, but only used if ADDRMAN_UNKNOWN_BUCKET_COUNT didn't
      * change, otherwise it is reconstructed as well.
      *
      * This format is more complex, but significantly smaller (at most 1.5 MiB),
      * and supports changes to the ADDRMAN_ parameters without breaking the
      * on-disk structure.
      *
      * We don't use SERIALIZE_METHODS since the serialization and
      * deserialization code has very little in common.
      */
     template <typename Stream> void Serialize(Stream &s_) const {
         LOCK(cs);
 
-        // Always serialize in the latest version (currently Format::V3_BIP155).
+        // Always serialize in the latest version (FILE_FORMAT).
 
         OverrideStream<Stream> s(&s_, s_.GetType(),
                                  s_.GetVersion() | ADDRV2_FORMAT);
 
-        s << static_cast<uint8_t>(Format::V3_BIP155);
-        s << uint8_t(32);
+        s << static_cast<uint8_t>(FILE_FORMAT);
+
+        // Increment `lowest_compatible` iff a newly introduced format is
+        // incompatible with the previous one.
+        static constexpr uint8_t lowest_compatible = Format::V3_BIP155;
+        s << static_cast<uint8_t>(INCOMPATIBILITY_BASE + lowest_compatible);
+
         s << nKey;
         s << nNew;
         s << nTried;
 
         int nUBuckets = ADDRMAN_NEW_BUCKET_COUNT ^ (1 << 30);
         s << nUBuckets;
         std::map<int, int> mapUnkIds;
         int nIds = 0;
         for (const auto &entry : mapInfo) {
             mapUnkIds[entry.first] = nIds;
             const CAddrInfo &info = entry.second;
             if (info.nRefCount) {
                 // this means nNew was wrong, oh ow
                 assert(nIds != nNew);
                 s << info;
                 nIds++;
             }
         }
         nIds = 0;
         for (const auto &entry : mapInfo) {
             const CAddrInfo &info = entry.second;
             if (info.fInTried) {
                 // this means nTried was wrong, oh ow
                 assert(nIds != nTried);
                 s << info;
                 nIds++;
             }
         }
         for (int bucket = 0; bucket < ADDRMAN_NEW_BUCKET_COUNT; bucket++) {
             int nSize = 0;
             for (int i = 0; i < ADDRMAN_BUCKET_SIZE; i++) {
                 if (vvNew[bucket][i] != -1) nSize++;
             }
             s << nSize;
             for (int i = 0; i < ADDRMAN_BUCKET_SIZE; i++) {
                 if (vvNew[bucket][i] != -1) {
                     int nIndex = mapUnkIds[vvNew[bucket][i]];
                     s << nIndex;
                 }
             }
         }
         // Store asmap version after bucket entries so that it
         // can be ignored by older clients for backward compatibility.
         uint256 asmap_version;
         if (m_asmap.size() != 0) {
             asmap_version = SerializeHash(m_asmap);
         }
         s << asmap_version;
     }
 
     template <typename Stream> void Unserialize(Stream &s_) {
         LOCK(cs);
 
         Clear();
 
         Format format;
         s_ >> Using<CustomUintFormatter<1>>(format);
 
-        static constexpr Format maximum_supported_format = Format::V3_BIP155;
-        if (format > maximum_supported_format) {
-            throw std::ios_base::failure(strprintf(
-                "Unsupported format of addrman database: %u. Maximum supported "
-                "is %u. "
-                "Continuing operation without using the saved list of peers.",
-                static_cast<uint8_t>(format),
-                static_cast<uint8_t>(maximum_supported_format)));
-        }
-
         int stream_version = s_.GetVersion();
         if (format >= Format::V3_BIP155) {
             // Add ADDRV2_FORMAT to the version so that the CNetAddr and
             // CAddress unserialize methods know that an address in addrv2
             // format is coming.
             stream_version |= ADDRV2_FORMAT;
         }
 
         OverrideStream<Stream> s(&s_, s_.GetType(), stream_version);
 
-        uint8_t nKeySize;
-        s >> nKeySize;
-        if (nKeySize != 32) {
-            throw std::ios_base::failure(
-                "Incorrect keysize in addrman deserialization");
+        uint8_t compat;
+        s >> compat;
+        const uint8_t lowest_compatible = compat - INCOMPATIBILITY_BASE;
+        if (lowest_compatible > FILE_FORMAT) {
+            throw std::ios_base::failure(strprintf(
+                "Unsupported format of addrman database: %u. It is compatible "
+                "with formats >=%u, "
+                "but the maximum supported by this version of %s is %u.",
+                format, lowest_compatible, PACKAGE_NAME,
+                static_cast<uint8_t>(FILE_FORMAT)));
         }
 
         s >> nKey;
         s >> nNew;
         s >> nTried;
         int nUBuckets = 0;
         s >> nUBuckets;
         if (format >= Format::V1_DETERMINISTIC) {
             nUBuckets ^= (1 << 30);
         }
 
         if (nNew > ADDRMAN_NEW_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE) {
             throw std::ios_base::failure(
                 "Corrupt CAddrMan serialization, nNew exceeds limit.");
         }
 
         if (nTried > ADDRMAN_TRIED_BUCKET_COUNT * ADDRMAN_BUCKET_SIZE) {
             throw std::ios_base::failure(
                 "Corrupt CAddrMan serialization, nTried exceeds limit.");
         }
 
         // Deserialize entries from the new table.
         for (int n = 0; n < nNew; n++) {
             CAddrInfo &info = mapInfo[n];
             s >> info;
             mapAddr[info] = n;
             info.nRandomPos = vRandom.size();
             vRandom.push_back(n);
         }
         nIdCount = nNew;
 
         // Deserialize entries from the tried table.
         int nLost = 0;
         for (int n = 0; n < nTried; n++) {
             CAddrInfo info;
             s >> info;
             int nKBucket = info.GetTriedBucket(nKey, m_asmap);
             int nKBucketPos = info.GetBucketPosition(nKey, false, nKBucket);
             if (vvTried[nKBucket][nKBucketPos] == -1) {
                 info.nRandomPos = vRandom.size();
                 info.fInTried = true;
                 vRandom.push_back(nIdCount);
                 mapInfo[nIdCount] = info;
                 mapAddr[info] = nIdCount;
                 vvTried[nKBucket][nKBucketPos] = nIdCount;
                 nIdCount++;
             } else {
                 nLost++;
             }
         }
         nTried -= nLost;
 
         // Store positions in the new table buckets to apply later (if
         // possible). Represents which entry belonged to which bucket when
         // serializing
         std::map<int, int> entryToBucket;
 
         for (int bucket = 0; bucket < nUBuckets; bucket++) {
             int nSize = 0;
             s >> nSize;
             for (int n = 0; n < nSize; n++) {
                 int nIndex = 0;
                 s >> nIndex;
                 if (nIndex >= 0 && nIndex < nNew) {
                     entryToBucket[nIndex] = bucket;
                 }
             }
         }
 
         uint256 supplied_asmap_version;
         if (m_asmap.size() != 0) {
             supplied_asmap_version = SerializeHash(m_asmap);
         }
         uint256 serialized_asmap_version;
         if (format >= Format::V2_ASMAP) {
             s >> serialized_asmap_version;
         }
 
         for (int n = 0; n < nNew; n++) {
             CAddrInfo &info = mapInfo[n];
             int bucket = entryToBucket[n];
             int nUBucketPos = info.GetBucketPosition(nKey, true, bucket);
             if (format >= Format::V2_ASMAP &&
                 nUBuckets == ADDRMAN_NEW_BUCKET_COUNT &&
                 vvNew[bucket][nUBucketPos] == -1 &&
                 info.nRefCount < ADDRMAN_NEW_BUCKETS_PER_ADDRESS &&
                 serialized_asmap_version == supplied_asmap_version) {
                 // Bucketing has not changed, using existing bucket positions
                 // for the new table
                 vvNew[bucket][nUBucketPos] = n;
                 info.nRefCount++;
             } else {
                 // In case the new table data cannot be used (format unknown,
                 // bucket count wrong or new asmap), try to give them a
                 // reference based on their primary source address.
                 LogPrint(BCLog::ADDRMAN,
                          "Bucketing method was updated, re-bucketing addrman "
                          "entries from disk\n");
                 bucket = info.GetNewBucket(nKey, m_asmap);
                 nUBucketPos = info.GetBucketPosition(nKey, true, bucket);
                 if (vvNew[bucket][nUBucketPos] == -1) {
                     vvNew[bucket][nUBucketPos] = n;
                     info.nRefCount++;
                 }
             }
         }
 
         // Prune new entries with refcount 0 (as a result of collisions).
         int nLostUnk = 0;
         for (std::map<int, CAddrInfo>::const_iterator it = mapInfo.begin();
              it != mapInfo.end();) {
             if (it->second.fInTried == false && it->second.nRefCount == 0) {
                 std::map<int, CAddrInfo>::const_iterator itCopy = it++;
                 Delete(itCopy->first);
                 nLostUnk++;
             } else {
                 it++;
             }
         }
         if (nLost + nLostUnk > 0) {
             LogPrint(BCLog::ADDRMAN,
                      "addrman lost %i new and %i tried addresses due to "
                      "collisions\n",
                      nLostUnk, nLost);
         }
 
         Check();
     }
 
     void Clear() {
         LOCK(cs);
         std::vector<int>().swap(vRandom);
         nKey = insecure_rand.rand256();
         for (size_t bucket = 0; bucket < ADDRMAN_NEW_BUCKET_COUNT; bucket++) {
             for (size_t entry = 0; entry < ADDRMAN_BUCKET_SIZE; entry++) {
                 vvNew[bucket][entry] = -1;
             }
         }
         for (size_t bucket = 0; bucket < ADDRMAN_TRIED_BUCKET_COUNT; bucket++) {
             for (size_t entry = 0; entry < ADDRMAN_BUCKET_SIZE; entry++) {
                 vvTried[bucket][entry] = -1;
             }
         }
 
         nIdCount = 0;
         nTried = 0;
         nNew = 0;
         // Initially at 1 so that "never" is strictly worse.
         nLastGood = 1;
         mapInfo.clear();
         mapAddr.clear();
     }
 
     CAddrMan() { Clear(); }
 
     ~CAddrMan() { nKey.SetNull(); }
 
     //! Return the number of (unique) addresses in all tables.
     size_t size() const {
         // TODO: Cache this in an atomic to avoid this overhead
         LOCK(cs);
         return vRandom.size();
     }
 
     //! Consistency check
     void Check() {
 #ifdef DEBUG_ADDRMAN
         {
             LOCK(cs);
             int err;
             if ((err = Check_())) {
                 LogPrintf("ADDRMAN CONSISTENCY CHECK FAILED!!! err=%i\n", err);
             }
         }
 #endif
     }
 
     //! Add a single address.
     bool Add(const CAddress &addr, const CNetAddr &source,
              int64_t nTimePenalty = 0) {
         LOCK(cs);
         bool fRet = false;
         Check();
         fRet |= Add_(addr, source, nTimePenalty);
         Check();
         if (fRet) {
             LogPrint(BCLog::ADDRMAN, "Added %s from %s: %i tried, %i new\n",
                      addr.ToStringIPPort(), source.ToString(), nTried, nNew);
         }
         return fRet;
     }
 
     //! Add multiple addresses.
     bool Add(const std::vector<CAddress> &vAddr, const CNetAddr &source,
              int64_t nTimePenalty = 0) {
         LOCK(cs);
         int nAdd = 0;
         Check();
         for (const CAddress &a : vAddr) {
             nAdd += Add_(a, source, nTimePenalty) ? 1 : 0;
         }
         Check();
         if (nAdd) {
             LogPrint(BCLog::ADDRMAN,
                      "Added %i addresses from %s: %i tried, %i new\n", nAdd,
                      source.ToString(), nTried, nNew);
         }
         return nAdd > 0;
     }
 
     //! Mark an entry as accessible.
     void Good(const CService &addr, bool test_before_evict = true,
               int64_t nTime = GetAdjustedTime()) {
         LOCK(cs);
         Check();
         Good_(addr, test_before_evict, nTime);
         Check();
     }
 
     //! Mark an entry as connection attempted to.
     void Attempt(const CService &addr, bool fCountFailure,
                  int64_t nTime = GetAdjustedTime()) {
         LOCK(cs);
         Check();
         Attempt_(addr, fCountFailure, nTime);
         Check();
     }
 
     //! See if any to-be-evicted tried table entries have been tested and if so
     //! resolve the collisions.
     void ResolveCollisions() {
         LOCK(cs);
         Check();
         ResolveCollisions_();
         Check();
     }
 
     //! Randomly select an address in tried that another address is attempting
     //! to evict.
     CAddrInfo SelectTriedCollision() {
         CAddrInfo ret;
         {
             LOCK(cs);
             Check();
             ret = SelectTriedCollision_();
             Check();
         }
         return ret;
     }
 
     /**
      * Choose an address to connect to.
      */
     CAddrInfo Select(bool newOnly = false) {
         CAddrInfo addrRet;
         {
             LOCK(cs);
             Check();
             addrRet = Select_(newOnly);
             Check();
         }
         return addrRet;
     }
 
     //! Return a bunch of addresses, selected at random.
     std::vector<CAddress> GetAddr() {
         Check();
         std::vector<CAddress> vAddr;
         {
             LOCK(cs);
             GetAddr_(vAddr);
         }
         Check();
         return vAddr;
     }
 
     //! Mark an entry as currently-connected-to.
     void Connected(const CService &addr, int64_t nTime = GetAdjustedTime()) {
         LOCK(cs);
         Check();
         Connected_(addr, nTime);
         Check();
     }
 
     void SetServices(const CService &addr, ServiceFlags nServices) {
         LOCK(cs);
         Check();
         SetServices_(addr, nServices);
         Check();
     }
 };
 
 #endif // BITCOIN_ADDRMAN_H