diff --git a/include/bitcoin/node/protocols/protocol_explore.hpp b/include/bitcoin/node/protocols/protocol_explore.hpp
index 902905a9..03120a66 100644
--- a/include/bitcoin/node/protocols/protocol_explore.hpp
+++ b/include/bitcoin/node/protocols/protocol_explore.hpp
@@ -72,36 +72,36 @@ class BCN_API protocol_explore
     ////bool handle_get_block_txs(const code& ec, interface::block_txs,
     ////    uint8_t version, uint8_t media, std::optional<system::hash_cptr> hash,
     ////    std::optional<uint32_t> height) NOEXCEPT;
-    ////
+
     ////bool handle_get_block_tx(const code& ec, interface::block_tx,
     ////    uint8_t version, uint8_t media, uint32_t position,
     ////    std::optional<system::hash_cptr> hash,
     ////    std::optional<uint32_t> height, bool witness) NOEXCEPT;
-    ////
+
     bool handle_get_transaction(const code& ec, interface::transaction,
-        uint8_t version, uint8_t media, system::hash_cptr hash,
+        uint8_t version, uint8_t media, const system::hash_cptr& hash,
         bool witness) NOEXCEPT;
     ////bool handle_get_address(const code& ec, interface::address,
-    ////    uint8_t version, uint8_t media, system::hash_cptr hash) NOEXCEPT;
-    ////
+    ////    uint8_t version, uint8_t media, const system::hash_cptr& hash) NOEXCEPT;
+
     ////bool handle_get_input(const code& ec, interface::input,
-    ////    uint8_t version, uint8_t media, system::hash_cptr hash,
+    ////    uint8_t version, uint8_t media, const system::hash_cptr& hash,
     ////    std::optional<uint32_t> index) NOEXCEPT;
     ////bool handle_get_input_script(const code& ec, interface::input_script,
-    ////    uint8_t version, uint8_t media, system::hash_cptr hash,
+    ////    uint8_t version, uint8_t media, const system::hash_cptr& hash,
     ////    std::optional<uint32_t> index) NOEXCEPT;
     ////bool handle_get_input_witness(const code& ec, interface::input_witness,
-    ////    uint8_t version, uint8_t media, system::hash_cptr hash,
+    ////    uint8_t version, uint8_t media, const system::hash_cptr& hash,
     ////    std::optional<uint32_t> index) NOEXCEPT;
-    ////
+
     ////bool handle_get_output(const code& ec, interface::output,
-    ////    uint8_t version, uint8_t media, system::hash_cptr hash,
+    ////    uint8_t version, uint8_t media, const system::hash_cptr& hash,
     ////    std::optional<uint32_t> index) NOEXCEPT;
     ////bool handle_get_output_script(const code& ec, interface::output_script,
-    ////    uint8_t version, uint8_t media, system::hash_cptr hash,
+    ////    uint8_t version, uint8_t media, const system::hash_cptr& hash,
     ////    std::optional<uint32_t> index) NOEXCEPT;
     ////bool handle_get_output_spender(const code& ec, interface::output_spender,
-    ////    uint8_t version, uint8_t media, system::hash_cptr hash,
+    ////    uint8_t version, uint8_t media, const system::hash_cptr& hash,
     ////    std::optional<uint32_t> index) NOEXCEPT;
 
 private:
diff --git a/src/full_node.cpp b/src/full_node.cpp
index 5bed9a1b..21e900b0 100644
--- a/src/full_node.cpp
+++ b/src/full_node.cpp
@@ -121,7 +121,7 @@ void full_node::do_run(const result_handler& handler) NOEXCEPT
 void full_node::start_web(const code& ec,
     const result_handler& handler) NOEXCEPT
 {
-    BC_ASSERT_MSG(stranded(), "strand");
+    BC_ASSERT(stranded());
 
     if (ec)
     {
@@ -136,7 +136,7 @@ void full_node::start_web(const code& ec,
 void full_node::start_explore(const code& ec,
     const result_handler& handler) NOEXCEPT
 {
-    BC_ASSERT_MSG(stranded(), "strand");
+    BC_ASSERT(stranded());
 
     if (ec)
     {
@@ -151,7 +151,7 @@ void full_node::start_explore(const code& ec,
 void full_node::start_websocket(const code& ec,
     const result_handler& handler) NOEXCEPT
 {
-    BC_ASSERT_MSG(stranded(), "strand");
+    BC_ASSERT(stranded());
 
     if (ec)
     {
@@ -166,7 +166,7 @@ void full_node::start_websocket(const code& ec,
 void full_node::start_bitcoind(const code& ec,
     const result_handler& handler) NOEXCEPT
 {
-    BC_ASSERT_MSG(stranded(), "strand");
+    BC_ASSERT(stranded());
 
     if (ec)
     {
@@ -181,7 +181,7 @@ void full_node::start_bitcoind(const code& ec,
 void full_node::start_electrum(const code& ec,
     const result_handler& handler) NOEXCEPT
 {
-    BC_ASSERT_MSG(stranded(), "strand");
+    BC_ASSERT(stranded());
 
     if (ec)
     {
@@ -196,7 +196,7 @@ void full_node::start_electrum(const code& ec,
 void full_node::start_stratum_v1(const code& ec,
     const result_handler& handler) NOEXCEPT
 {
-    BC_ASSERT_MSG(stranded(), "strand");
+    BC_ASSERT(stranded());
 
     if (ec)
     {
@@ -211,7 +211,7 @@ void full_node::start_stratum_v1(const code& ec,
 void full_node::start_stratum_v2(const code& ec,
     const result_handler& handler) NOEXCEPT
 {
-    BC_ASSERT_MSG(stranded(), "strand");
+    BC_ASSERT(stranded());
 
     if (ec)
     {
diff --git a/src/protocols/protocol_explore.cpp b/src/protocols/protocol_explore.cpp
index 6041f939..d51ad1ba 100644
--- a/src/protocols/protocol_explore.cpp
+++ b/src/protocols/protocol_explore.cpp
@@ -39,6 +39,9 @@ using namespace std::placeholders;
 using object_type = network::rpc::object_t;
 
 BC_PUSH_WARNING(NO_THROW_IN_NOEXCEPT)
+BC_PUSH_WARNING(NO_INCOMPLETE_SWITCH)
+BC_PUSH_WARNING(SMART_PTR_NOT_NEEDED)
+BC_PUSH_WARNING(NO_VALUE_OR_CONST_REF_SHARED_PTR)
 
 // Start.
 // ----------------------------------------------------------------------------
@@ -98,7 +101,7 @@ bool protocol_explore::try_dispatch_object(const request& request) NOEXCEPT
 // ----------------------------------------------------------------------------
 
 bool protocol_explore::handle_get_block(const code& ec, interface::block,
-    uint8_t, uint8_t media, std::optional<system::hash_cptr> hash,
+    uint8_t, uint8_t media, std::optional<hash_cptr> hash,
     std::optional<uint32_t> height, bool witness) NOEXCEPT
 {
     BC_ASSERT(stranded());
@@ -107,8 +110,9 @@ bool protocol_explore::handle_get_block(const code& ec, interface::block,
         return false;
 
     const auto& query = archive();
-    const auto link = hash.has_value() ? query.to_header(*(hash.value())) :
-        query.to_confirmed(height.value());
+    const auto link = hash.has_value() ?
+        query.to_header(*(hash.value())) : (height.has_value() ?
+            query.to_confirmed(height.value()) : database::header_link{});
 
     // TODO: there's no request.
     const network::http::request request{};
@@ -135,7 +139,7 @@ bool protocol_explore::handle_get_block(const code& ec, interface::block,
 }
 
 bool protocol_explore::handle_get_header(const code& ec, interface::header,
-    uint8_t, uint8_t media, std::optional<system::hash_cptr> hash,
+    uint8_t, uint8_t media, std::optional<hash_cptr> hash,
     std::optional<uint32_t> height) NOEXCEPT
 {
     BC_ASSERT(stranded());
@@ -144,8 +148,9 @@ bool protocol_explore::handle_get_header(const code& ec, interface::header,
         return false;
 
     const auto& query = archive();
-    const auto link = hash.has_value() ? query.to_header(*(hash.value())) :
-        query.to_confirmed(height.value());
+    const auto link = hash.has_value() ?
+        query.to_header(*(hash.value())) : (height.has_value() ?
+            query.to_confirmed(height.value()) : database::header_link{});
 
     // TODO: there's no request.
     const network::http::request request{};
@@ -172,7 +177,7 @@ bool protocol_explore::handle_get_header(const code& ec, interface::header,
 }
 
 bool protocol_explore::handle_get_transaction(const code& ec,
-    interface::transaction, uint8_t, uint8_t media, system::hash_cptr hash,
+    interface::transaction, uint8_t, uint8_t media, const hash_cptr& hash,
     bool witness) NOEXCEPT
 {
     BC_ASSERT(stranded());
@@ -206,6 +211,9 @@ bool protocol_explore::handle_get_transaction(const code& ec,
     return true;
 }
 
+BC_POP_WARNING()
+BC_POP_WARNING()
+BC_POP_WARNING()
 BC_POP_WARNING()
 
 #undef SUBSCRIBE_EXPLORE