diff --git a/src/txdb.cpp b/src/txdb.cpp
index af481868b..dda45692c 100644
--- a/src/txdb.cpp
+++ b/src/txdb.cpp
@@ -1,567 +1,499 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
 // Copyright (c) 2009-2018 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
 #include <txdb.h>
 
-#include <blockdb.h>
 #include <chain.h>
 #include <node/ui_interface.h>
 #include <pow/pow.h>
 #include <random.h>
 #include <shutdown.h>
 #include <util/system.h>
 #include <util/translation.h>
 #include <util/vector.h>
 #include <version.h>
 
 #include <cstdint>
 #include <memory>
 
 static const char DB_COIN = 'C';
 static const char DB_COINS = 'c';
 static const char DB_BLOCK_FILES = 'f';
 static const char DB_BLOCK_INDEX = 'b';
 
 static const char DB_BEST_BLOCK = 'B';
 static const char DB_HEAD_BLOCKS = 'H';
 static const char DB_FLAG = 'F';
 static const char DB_REINDEX_FLAG = 'R';
 static const char DB_LAST_BLOCK = 'l';
 
 namespace {
 
 struct CoinEntry {
     COutPoint *outpoint;
     char key;
     explicit CoinEntry(const COutPoint *ptr)
         : outpoint(const_cast<COutPoint *>(ptr)), key(DB_COIN) {}
 
     SERIALIZE_METHODS(CoinEntry, obj) {
         TxId id = obj.outpoint->GetTxId();
         uint32_t n = obj.outpoint->GetN();
         READWRITE(obj.key, id, VARINT(n));
         SER_READ(obj, *obj.outpoint = COutPoint(id, n));
     }
 };
 } // namespace
 
 CCoinsViewDB::CCoinsViewDB(fs::path ldb_path, size_t nCacheSize, bool fMemory,
                            bool fWipe)
     : m_db(std::make_unique<CDBWrapper>(ldb_path, nCacheSize, fMemory, fWipe,
                                         true)),
       m_ldb_path(ldb_path), m_is_memory(fMemory) {}
 
 void CCoinsViewDB::ResizeCache(size_t new_cache_size) {
     // We can't do this operation with an in-memory DB since we'll lose all the
     // coins upon reset.
     if (!m_is_memory) {
         // Have to do a reset first to get the original `m_db` state to release
         // its filesystem lock.
         m_db.reset();
         m_db = std::make_unique<CDBWrapper>(m_ldb_path, new_cache_size,
                                             m_is_memory, /*fWipe*/ false,
                                             /*obfuscate*/ true);
     }
 }
 
 bool CCoinsViewDB::GetCoin(const COutPoint &outpoint, Coin &coin) const {
     return m_db->Read(CoinEntry(&outpoint), coin);
 }
 
 bool CCoinsViewDB::HaveCoin(const COutPoint &outpoint) const {
     return m_db->Exists(CoinEntry(&outpoint));
 }
 
 BlockHash CCoinsViewDB::GetBestBlock() const {
     BlockHash hashBestChain;
     if (!m_db->Read(DB_BEST_BLOCK, hashBestChain)) {
         return BlockHash();
     }
     return hashBestChain;
 }
 
 std::vector<BlockHash> CCoinsViewDB::GetHeadBlocks() const {
     std::vector<BlockHash> vhashHeadBlocks;
     if (!m_db->Read(DB_HEAD_BLOCKS, vhashHeadBlocks)) {
         return std::vector<BlockHash>();
     }
     return vhashHeadBlocks;
 }
 
 bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const BlockHash &hashBlock) {
     CDBBatch batch(*m_db);
     size_t count = 0;
     size_t changed = 0;
     size_t batch_size =
         (size_t)gArgs.GetArg("-dbbatchsize", DEFAULT_DB_BATCH_SIZE);
     int crash_simulate = gArgs.GetArg("-dbcrashratio", 0);
     assert(!hashBlock.IsNull());
 
     BlockHash old_tip = GetBestBlock();
     if (old_tip.IsNull()) {
         // We may be in the middle of replaying.
         std::vector<BlockHash> old_heads = GetHeadBlocks();
         if (old_heads.size() == 2) {
             assert(old_heads[0] == hashBlock);
             old_tip = old_heads[1];
         }
     }
 
     // In the first batch, mark the database as being in the middle of a
     // transition from old_tip to hashBlock.
     // A vector is used for future extensibility, as we may want to support
     // interrupting after partial writes from multiple independent reorgs.
     batch.Erase(DB_BEST_BLOCK);
     batch.Write(DB_HEAD_BLOCKS, Vector(hashBlock, old_tip));
 
     for (CCoinsMap::iterator it = mapCoins.begin(); it != mapCoins.end();) {
         if (it->second.flags & CCoinsCacheEntry::DIRTY) {
             CoinEntry entry(&it->first);
             if (it->second.coin.IsSpent()) {
                 batch.Erase(entry);
             } else {
                 batch.Write(entry, it->second.coin);
             }
             changed++;
         }
         count++;
         CCoinsMap::iterator itOld = it++;
         mapCoins.erase(itOld);
         if (batch.SizeEstimate() > batch_size) {
             LogPrint(BCLog::COINDB, "Writing partial batch of %.2f MiB\n",
                      batch.SizeEstimate() * (1.0 / 1048576.0));
             m_db->WriteBatch(batch);
             batch.Clear();
             if (crash_simulate) {
                 static FastRandomContext rng;
                 if (rng.randrange(crash_simulate) == 0) {
                     LogPrintf("Simulating a crash. Goodbye.\n");
                     _Exit(0);
                 }
             }
         }
     }
 
     // In the last batch, mark the database as consistent with hashBlock again.
     batch.Erase(DB_HEAD_BLOCKS);
     batch.Write(DB_BEST_BLOCK, hashBlock);
 
     LogPrint(BCLog::COINDB, "Writing final batch of %.2f MiB\n",
              batch.SizeEstimate() * (1.0 / 1048576.0));
     bool ret = m_db->WriteBatch(batch);
     LogPrint(BCLog::COINDB,
              "Committed %u changed transaction outputs (out of "
              "%u) to coin database...\n",
              (unsigned int)changed, (unsigned int)count);
     return ret;
 }
 
 size_t CCoinsViewDB::EstimateSize() const {
     return m_db->EstimateSize(DB_COIN, char(DB_COIN + 1));
 }
 
 CBlockTreeDB::CBlockTreeDB(size_t nCacheSize, bool fMemory, bool fWipe)
     : CDBWrapper(GetDataDir() / "blocks" / "index", nCacheSize, fMemory,
                  fWipe) {}
 
 bool CBlockTreeDB::ReadBlockFileInfo(int nFile, CBlockFileInfo &info) {
     return Read(std::make_pair(DB_BLOCK_FILES, nFile), info);
 }
 
 bool CBlockTreeDB::WriteReindexing(bool fReindexing) {
     if (fReindexing) {
         return Write(DB_REINDEX_FLAG, '1');
     } else {
         return Erase(DB_REINDEX_FLAG);
     }
 }
 
 bool CBlockTreeDB::IsReindexing() const {
     return Exists(DB_REINDEX_FLAG);
 }
 
 bool CBlockTreeDB::ReadLastBlockFile(int &nFile) {
     return Read(DB_LAST_BLOCK, nFile);
 }
 
 CCoinsViewCursor *CCoinsViewDB::Cursor() const {
     CCoinsViewDBCursor *i = new CCoinsViewDBCursor(
         const_cast<CDBWrapper &>(*m_db).NewIterator(), GetBestBlock());
     /**
      * It seems that there are no "const iterators" for LevelDB. Since we only
      * need read operations on it, use a const-cast to get around that
      * restriction.
      */
     i->pcursor->Seek(DB_COIN);
     // Cache key of first record
     if (i->pcursor->Valid()) {
         CoinEntry entry(&i->keyTmp.second);
         i->pcursor->GetKey(entry);
         i->keyTmp.first = entry.key;
     } else {
         // Make sure Valid() and GetKey() return false
         i->keyTmp.first = 0;
     }
     return i;
 }
 
 bool CCoinsViewDBCursor::GetKey(COutPoint &key) const {
     // Return cached key
     if (keyTmp.first == DB_COIN) {
         key = keyTmp.second;
         return true;
     }
     return false;
 }
 
 bool CCoinsViewDBCursor::GetValue(Coin &coin) const {
     return pcursor->GetValue(coin);
 }
 
 unsigned int CCoinsViewDBCursor::GetValueSize() const {
     return pcursor->GetValueSize();
 }
 
 bool CCoinsViewDBCursor::Valid() const {
     return keyTmp.first == DB_COIN;
 }
 
 void CCoinsViewDBCursor::Next() {
     pcursor->Next();
     CoinEntry entry(&keyTmp.second);
     if (!pcursor->Valid() || !pcursor->GetKey(entry)) {
         // Invalidate cached key after last record so that Valid() and GetKey()
         // return false
         keyTmp.first = 0;
     } else {
         keyTmp.first = entry.key;
     }
 }
 
 bool CBlockTreeDB::WriteBatchSync(
     const std::vector<std::pair<int, const CBlockFileInfo *>> &fileInfo,
     int nLastFile, const std::vector<const CBlockIndex *> &blockinfo) {
     CDBBatch batch(*this);
     for (std::vector<std::pair<int, const CBlockFileInfo *>>::const_iterator
              it = fileInfo.begin();
          it != fileInfo.end(); it++) {
         batch.Write(std::make_pair(DB_BLOCK_FILES, it->first), *it->second);
     }
     batch.Write(DB_LAST_BLOCK, nLastFile);
     for (std::vector<const CBlockIndex *>::const_iterator it =
              blockinfo.begin();
          it != blockinfo.end(); it++) {
         batch.Write(std::make_pair(DB_BLOCK_INDEX, (*it)->GetBlockHash()),
                     CDiskBlockIndex(*it));
     }
     return WriteBatch(batch, true);
 }
 
 bool CBlockTreeDB::WriteFlag(const std::string &name, bool fValue) {
     return Write(std::make_pair(DB_FLAG, name), fValue ? '1' : '0');
 }
 
 bool CBlockTreeDB::ReadFlag(const std::string &name, bool &fValue) {
     char ch;
     if (!Read(std::make_pair(DB_FLAG, name), ch)) {
         return false;
     }
     fValue = ch == '1';
     return true;
 }
 
 bool CBlockTreeDB::LoadBlockIndexGuts(
     const Consensus::Params &params,
     std::function<CBlockIndex *(const BlockHash &)> insertBlockIndex) {
     std::unique_ptr<CDBIterator> pcursor(NewIterator());
 
     uint64_t version = 0;
     pcursor->Seek("version");
     if (pcursor->Valid()) {
         pcursor->GetValue(version);
     }
 
     if (version != CLIENT_VERSION) {
         return error("%s: Invalid block index database version: %s", __func__,
                      version);
     }
 
     pcursor->Seek(std::make_pair(DB_BLOCK_INDEX, uint256()));
 
     // Load m_block_index
     while (pcursor->Valid()) {
         if (ShutdownRequested()) {
             return false;
         }
         std::pair<char, uint256> key;
         if (!pcursor->GetKey(key) || key.first != DB_BLOCK_INDEX) {
             break;
         }
 
         CDiskBlockIndex diskindex;
         if (!pcursor->GetValue(diskindex)) {
             return error("%s : failed to read value", __func__);
         }
 
         // Construct block index object
         CBlockIndex *pindexNew = insertBlockIndex(diskindex.GetBlockHash());
         pindexNew->pprev = insertBlockIndex(diskindex.hashPrev);
         pindexNew->nHeight = diskindex.nHeight;
         pindexNew->nFile = diskindex.nFile;
         pindexNew->nDataPos = diskindex.nDataPos;
         pindexNew->nUndoPos = diskindex.nUndoPos;
         pindexNew->nVersion = diskindex.nVersion;
         pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
         pindexNew->nTime = diskindex.nTime;
         pindexNew->nBits = diskindex.nBits;
         pindexNew->nNonce = diskindex.nNonce;
         pindexNew->nStatus = diskindex.nStatus;
         pindexNew->nTx = diskindex.nTx;
 
         if (!CheckProofOfWork(pindexNew->GetBlockHash(), pindexNew->nBits,
                               params)) {
             return error("%s: CheckProofOfWork failed: %s", __func__,
                          pindexNew->ToString());
         }
 
         pcursor->Next();
     }
 
     return true;
 }
 
 namespace {
 //! Legacy class to deserialize pre-pertxout database entries without reindex.
 class CCoins {
 public:
     //! whether transaction is a coinbase
     bool fCoinBase;
 
     //! unspent transaction outputs; spent outputs are .IsNull(); spent outputs
     //! at the end of the array are dropped
     std::vector<CTxOut> vout;
 
     //! at which height this transaction was included in the active block chain
     int nHeight;
 
     //! empty constructor
     CCoins() : fCoinBase(false), vout(0), nHeight(0) {}
 
     template <typename Stream> void Unserialize(Stream &s) {
         uint32_t nCode = 0;
         // version
         unsigned int nVersionDummy = 0;
         ::Unserialize(s, VARINT(nVersionDummy));
         // header code
         ::Unserialize(s, VARINT(nCode));
         fCoinBase = nCode & 1;
         std::vector<bool> vAvail(2, false);
         vAvail[0] = (nCode & 2) != 0;
         vAvail[1] = (nCode & 4) != 0;
         uint32_t nMaskCode = (nCode / 8) + ((nCode & 6) != 0 ? 0 : 1);
         // spentness bitmask
         while (nMaskCode > 0) {
             uint8_t chAvail = 0;
             ::Unserialize(s, chAvail);
             for (unsigned int p = 0; p < 8; p++) {
                 bool f = (chAvail & (1 << p)) != 0;
                 vAvail.push_back(f);
             }
             if (chAvail != 0) {
                 nMaskCode--;
             }
         }
         // txouts themself
         vout.assign(vAvail.size(), CTxOut());
         for (size_t i = 0; i < vAvail.size(); i++) {
             if (vAvail[i]) {
                 ::Unserialize(s, Using<TxOutCompression>(vout[i]));
             }
         }
         // coinbase height
         ::Unserialize(s, VARINT_MODE(nHeight, VarIntMode::NONNEGATIVE_SIGNED));
     }
 };
 } // namespace
 
 /**
  * Upgrade the database from older formats.
  *
  * Currently implemented: from the per-tx utxo model (0.8..0.14.x) to per-txout.
  */
 bool CCoinsViewDB::Upgrade() {
     std::unique_ptr<CDBIterator> pcursor(m_db->NewIterator());
     pcursor->Seek(std::make_pair(DB_COINS, uint256()));
     if (!pcursor->Valid()) {
         return true;
     }
 
     int64_t count = 0;
     LogPrintf("Upgrading utxo-set database...\n");
     size_t batch_size = 1 << 24;
     CDBBatch batch(*m_db);
     int reportDone = -1;
     std::pair<uint8_t, uint256> key;
     std::pair<uint8_t, uint256> prev_key = {DB_COINS, uint256()};
     while (pcursor->Valid()) {
         if (ShutdownRequested()) {
             break;
         }
 
         if (!pcursor->GetKey(key) || key.first != DB_COINS) {
             break;
         }
 
         if (count++ % 256 == 0) {
             uint32_t high =
                 0x100 * *key.second.begin() + *(key.second.begin() + 1);
             int percentageDone = (int)(high * 100.0 / 65536.0 + 0.5);
             uiInterface.ShowProgress(_("Upgrading UTXO database").translated,
                                      percentageDone, true);
             if (reportDone < percentageDone / 10) {
                 // report max. every 10% step
                 LogPrintfToBeContinued("[%d%%]...", percentageDone);
                 reportDone = percentageDone / 10;
             }
         }
 
         CCoins old_coins;
         if (!pcursor->GetValue(old_coins)) {
             return error("%s: cannot parse CCoins record", __func__);
         }
 
         const TxId id(key.second);
         for (size_t i = 0; i < old_coins.vout.size(); ++i) {
             if (!old_coins.vout[i].IsNull() &&
                 !old_coins.vout[i].scriptPubKey.IsUnspendable()) {
                 Coin newcoin(std::move(old_coins.vout[i]), old_coins.nHeight,
                              old_coins.fCoinBase);
                 COutPoint outpoint(id, i);
                 CoinEntry entry(&outpoint);
                 batch.Write(entry, newcoin);
             }
         }
 
         batch.Erase(key);
         if (batch.SizeEstimate() > batch_size) {
             m_db->WriteBatch(batch);
             batch.Clear();
             m_db->CompactRange(prev_key, key);
             prev_key = key;
         }
 
         pcursor->Next();
     }
 
     m_db->WriteBatch(batch);
     m_db->CompactRange({DB_COINS, uint256()}, key);
     uiInterface.ShowProgress("", 100, false);
     LogPrintf("[%s].\n", ShutdownRequested() ? "CANCELLED" : "DONE");
     return !ShutdownRequested();
 }
 
 bool CBlockTreeDB::Upgrade(const Consensus::Params &params) {
+    // This method used to add the block size to pre-0.22.8 block index
+    // databases. This is no longer supported as of 0.25.5, but the method is
+    // kept to update the version number in the database.
     std::unique_ptr<CDBIterator> pcursor(NewIterator());
 
     uint64_t version = 0;
     pcursor->Seek("version");
     if (pcursor->Valid()) {
         pcursor->GetValue(version);
     }
 
     if (version >= CLIENT_VERSION) {
         // The DB is already up to date.
         return true;
     }
 
-    CDBBatch batch(*this);
-
     pcursor->Seek(std::make_pair(DB_BLOCK_INDEX, uint256()));
-    if (!pcursor->Valid()) {
-        // The DB is empty, so just write the version number and consider the
-        // upgrade done.
-        batch.Write("version", uint64_t(CLIENT_VERSION));
-        WriteBatch(batch);
-        return true;
-    }
-
-    int64_t count = 0;
-    LogPrintf("Upgrading block index database...\n");
-    int reportDone = -1;
-    std::pair<uint8_t, uint256> key = {DB_BLOCK_INDEX, uint256()};
-    while (pcursor->Valid()) {
-        if (ShutdownRequested()) {
-            break;
-        }
-
-        if (!pcursor->GetKey(key) || key.first != DB_BLOCK_INDEX) {
-            break;
-        }
-
-        if (count++ % 256 == 0) {
-            uint32_t high =
-                0x100 * *key.second.begin() + *(key.second.begin() + 1);
-            int percentageDone = (int)(high * 100.0 / 65536.0 + 0.5);
-            uiInterface.ShowProgress(
-                _("Upgrading block index database").translated, percentageDone,
-                true);
-            if (reportDone < percentageDone / 10) {
-                // report max. every 10% step
-                LogPrintfToBeContinued("[%d%%]...", percentageDone);
-                reportDone = percentageDone / 10;
-            }
-        }
-
-        // Read the block index entry and update it.
-        CDiskBlockIndex diskindex;
-        if (!pcursor->GetValue(diskindex)) {
-            return error("%s: cannot parse CDiskBlockIndex record", __func__);
-        }
-
-        // The block hash needs to be usable.
-        BlockHash blockhash = diskindex.GetBlockHash();
-        diskindex.phashBlock = &blockhash;
-
-        bool mustUpdate = false;
-
-        // We must update the block index to add the size.
-        if (CLIENT_VERSION >= CDiskBlockIndex::TRACK_SIZE_VERSION &&
-            version < CDiskBlockIndex::TRACK_SIZE_VERSION &&
-            diskindex.nTx > 0 && diskindex.nSize == 0) {
-            if (!diskindex.nStatus.hasData()) {
-                // The block was pruned, we need a full reindex.
-                LogPrintf("\nThe block %s is pruned. The block index cannot be "
-                          "upgraded and reindexing is required.\n",
-                          blockhash.GetHex());
-                return false;
-            }
-
-            CBlock block;
-            if (!ReadBlockFromDisk(block, &diskindex, params)) {
-                // Failed to read the block from disk, even though it is marked
-                // that we have data for this block.
-                return false;
-            }
 
-            mustUpdate = true;
-            diskindex.nSize = ::GetSerializeSize(block, PROTOCOL_VERSION);
-        }
-
-        if (mustUpdate) {
-            batch.Write(std::make_pair(DB_BLOCK_INDEX, blockhash), diskindex);
-        }
-
-        pcursor->Next();
+    // The DB is not empty, and the version is either non-existent or too old.
+    // The node requires a reindex.
+    if (pcursor->Valid() && version < CDiskBlockIndex::TRACK_SIZE_VERSION) {
+        LogPrintf(
+            "\nThe database is too old. The block index cannot be upgraded "
+            "and reindexing is required.\n");
+        return false;
     }
 
-    // Upgrade is done, now let's update the version number.
+    // The DB is empty or recent enough.
+    // Just write the new version number and consider the upgrade done.
+    CDBBatch batch(*this);
+    LogPrintf("Updating the block index database version to %d\n",
+              CLIENT_VERSION);
     batch.Write("version", uint64_t(CLIENT_VERSION));
-
-    WriteBatch(batch);
-    CompactRange({DB_BLOCK_INDEX, uint256()}, key);
-    uiInterface.ShowProgress("", 100, false);
-    LogPrintf("[%s].\n", ShutdownRequested() ? "CANCELLED" : "DONE");
-    return !ShutdownRequested();
+    return WriteBatch(batch);
 }