diff --git a/src/lelantus.cpp b/src/lelantus.cpp
index 7b6df0a744..95e45e2fab 100644
--- a/src/lelantus.cpp
+++ b/src/lelantus.cpp
@@ -553,6 +553,13 @@ bool CheckLelantusJoinSplitTransaction(
         anonymity_sets[idAndHash.first] = anonymity_set;
     }
 
+    const std::vector<uint32_t>& ids = joinsplit->getCoinGroupIds();
+    for (const auto& id: ids) {
+        if (!anonymity_sets.count(id))
+            return state.DoS(100,
+                             error("CheckLelantusJoinSplitTransaction: No anonymity set found."));
+    }
+
     BatchProofContainer* batchProofContainer = BatchProofContainer::get_instance();
     bool useBatching = batchProofContainer->fCollectProofs && !isVerifyDB && !isCheckWallet && lelantusTxInfo && !lelantusTxInfo->fInfoIsComplete;
 
@@ -941,15 +948,17 @@ bool ConnectBlockLelantus(
                     )) {
                 return false;
             }
+        }
 
-            if (!fJustCheck) {
+        if (!fJustCheck) {
+            BOOST_FOREACH(auto& serial, pblock->lelantusTxInfo->spentSerials) {
                 pindexNew->lelantusSpentSerials.insert(serial);
                 lelantusState.AddSpend(serial.first, serial.second);
             }
         }
-
-        if (fJustCheck)
+        else {
             return true;
+        }
 
         const auto& params = ::Params().GetConsensus();
         CHash256 hash;
@@ -1359,9 +1368,8 @@ void CLelantusState::RemoveBlock(CBlockIndex *index) {
     // roll back coin group updates
     for (auto &coins : index->lelantusMintedPubCoins)
     {
-        if (coinGroups.count(coins.first) == 0) {
-            throw std::invalid_argument("Group Id does not exist");
-        }
+        if (coinGroups.count(coins.first) == 0)
+            continue;
 
         LelantusCoinGroupInfo& coinGroup = coinGroups[coins.first];
         auto nMintsToForget = coins.second.size();
diff --git a/src/qt/sendcoinsdialog.cpp b/src/qt/sendcoinsdialog.cpp
index 5480410cbd..3f514961f7 100644
--- a/src/qt/sendcoinsdialog.cpp
+++ b/src/qt/sendcoinsdialog.cpp
@@ -320,7 +320,7 @@ void SendCoinsDialog::on_sendButton_clicked()
     CAmount mintSparkAmount = 0;
     CAmount txFee = 0;
     CAmount totalAmount = 0;
-    if (model->getLelantusModel()->getPrivateBalance().first > 0 && chainActive.Height() < ::Params().GetConsensus().nLelantusGracefulPeriod) {
+    if (model->getLelantusModel()->getPrivateBalance().first > 0 && spark::IsSparkAllowed() && chainActive.Height() < ::Params().GetConsensus().nLelantusGracefulPeriod) {
         MigrateLelantusToSparkDialog migrateLelantusToSpark(model);
         bool clickedButton = migrateLelantusToSpark.getClickedButton();
         if(clickedButton) {
@@ -332,16 +332,23 @@ void SendCoinsDialog::on_sendButton_clicked()
         prepareStatus = model->prepareJoinSplitTransaction(currentTransaction, &ctrl);
     } else if ((fAnonymousMode == true) && spark::IsSparkAllowed()) {
         prepareStatus = model->prepareSpendSparkTransaction(currentTransaction, &ctrl);
-    } else if ((fAnonymousMode == false) && (recipients.size() == sparkAddressCount) && spark::IsSparkAllowed()) {
-        prepareStatus = model->prepareMintSparkTransaction(transactions, recipients, wtxAndFees, reservekeys, &ctrl);
-    } else if ((fAnonymousMode == false) && (sparkAddressCount == 0)){
-        SendGoPrivateDialog goPrivateDialog;
-        bool clickedButton = goPrivateDialog.getClickedButton();
-        if(clickedButton) {
-            setAnonymizeMode(true);
-            fNewRecipientAllowed = true;
+    } else if ((fAnonymousMode == false) && (recipients.size() == sparkAddressCount)) {
+        if (spark::IsSparkAllowed())
+            prepareStatus = model->prepareMintSparkTransaction(transactions, recipients, wtxAndFees, reservekeys, &ctrl);
+        else {
+            processSendCoinsReturn(WalletModel::InvalidAddress);
             return;
         }
+    } else if ((fAnonymousMode == false) && (sparkAddressCount == 0)) {
+        if (spark::IsSparkAllowed()) {
+            SendGoPrivateDialog goPrivateDialog;
+            bool clickedButton = goPrivateDialog.getClickedButton();
+            if (clickedButton) {
+                setAnonymizeMode(true);
+                fNewRecipientAllowed = true;
+                return;
+            }
+        }
         prepareStatus = model->prepareTransaction(currentTransaction, &ctrl);
     } else {
         fNewRecipientAllowed = true;
diff --git a/src/sigma.cpp b/src/sigma.cpp
index 23236241e6..36c9a1e044 100644
--- a/src/sigma.cpp
+++ b/src/sigma.cpp
@@ -643,15 +643,17 @@ bool ConnectBlockSigma(
                     )) {
                 return false;
             }
+        }
 
-            if (!fJustCheck) {
+        if (!fJustCheck) {
+            BOOST_FOREACH(auto& serial, pblock->sigmaTxInfo->spentSerials) {
                 pindexNew->sigmaSpentSerials.insert(serial);
                 sigmaState.AddSpend(serial.first, serial.second.denomination, serial.second.coinGroupId);
             }
         }
-
-        if (fJustCheck)
+        else {
             return true;
+        }
 
         sigmaState.AddMintsToStateAndBlockIndex(pindexNew, pblock);
     }
diff --git a/src/validation.cpp b/src/validation.cpp
index f7b5db1653..f5c542cd53 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -723,7 +723,7 @@ bool CheckTransaction(const CTransaction &tx, CValidationState &state, bool fChe
         LOCK(cs_main);
         nTxHeight = chainActive.Height();
     }
-    if (hasExchangeUTXOs && !isCheckWallet && !isVerifyDB && nTxHeight < ::Params().GetConsensus().nExchangeAddressStartBlock)
+    if (hasExchangeUTXOs && !isVerifyDB && nTxHeight < ::Params().GetConsensus().nExchangeAddressStartBlock)
         return state.DoS(100, false, REJECT_INVALID, "bad-exchange-address");
 
     if (tx.IsCoinBase())