diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -1603,7 +1603,6 @@
         if (!pblockindex) {
             throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
         }
-
         FinalizeBlockAndInvalidate(config, state, pblockindex);
     }
 
diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -2830,6 +2830,14 @@
     }
 }
 
+static void LimitValidationInterfaceQueue() {
+    AssertLockNotHeld(cs_main);
+
+    if (GetMainSignals().CallbacksPending() > 10) {
+        SyncWithValidationInterfaceQueue();
+    }
+}
+
 /**
  * Make the best chain active, in multiple steps. The result is either failure
  * or an activated best chain. pblock is either nullptr or a pointer to a block
@@ -2864,15 +2872,13 @@
     do {
         boost::this_thread::interruption_point();
 
-        if (GetMainSignals().CallbacksPending() > 10) {
-            // Block until the validation queue drains. This should largely
-            // never happen in normal operation, however may happen during
-            // reindex, causing memory blowup if we run too far ahead.
-            // Note that if a validationinterface callback ends up calling
-            // ActivateBestChain this may lead to a deadlock! We should
-            // probably have a DEBUG_LOCKORDER test for this in the future.
-            SyncWithValidationInterfaceQueue();
-        }
+        // Block until the validation queue drains. This should largely
+        // never happen in normal operation, however may happen during
+        // reindex, causing memory blowup if we run too far ahead.
+        // Note that if a validationinterface callback ends up calling
+        // ActivateBestChain this may lead to a deadlock! We should
+        // probably have a DEBUG_LOCKORDER test for this in the future.
+        LimitValidationInterfaceQueue();
 
         {
             LOCK(cs_main);
@@ -3035,6 +3041,9 @@
             break;
         }
 
+        // Make sure the queue of validation callbacks doesn't grow unboundedly.
+        LimitValidationInterfaceQueue();
+
         LOCK(cs_main);
 
         if (!chainActive.Contains(pindex)) {