diff --git a/src/ipc/capnp/mining-types.h b/src/ipc/capnp/mining-types.h
index 2e60b43fcf3..62789759490 100644
--- a/src/ipc/capnp/mining-types.h
+++ b/src/ipc/capnp/mining-types.h
@@ -14,13 +14,7 @@
 #include <validation.h>
 
 namespace mp {
-// Custom serialization for BlockValidationState.
-void CustomBuildMessage(InvokeContext& invoke_context,
-                        const BlockValidationState& src,
-                        ipc::capnp::messages::BlockValidationState::Builder&& builder);
-void CustomReadMessage(InvokeContext& invoke_context,
-                       const ipc::capnp::messages::BlockValidationState::Reader& reader,
-                       BlockValidationState& dest);
+// Custom serializations
 } // namespace mp
 
 #endif // BITCOIN_IPC_CAPNP_MINING_TYPES_H
diff --git a/src/ipc/capnp/mining.capnp b/src/ipc/capnp/mining.capnp
index 32048e0ed19..f3327bf2e7b 100644
--- a/src/ipc/capnp/mining.capnp
+++ b/src/ipc/capnp/mining.capnp
@@ -44,13 +44,3 @@ struct BlockWaitOptions $Proxy.wrap("node::BlockWaitOptions") {
     timeout @0 : Float64 $Proxy.name("timeout");
     feeThreshold @1 : Int64 $Proxy.name("fee_threshold");
 }
-
-# Note: serialization of the BlockValidationState C++ type is somewhat fragile
-# and using the struct can be awkward. It would be good if testBlockValidity
-# method were changed to return validity information in a simpler format.
-struct BlockValidationState {
-    mode @0 :Int32;
-    result @1 :Int32;
-    rejectReason @2 :Text;
-    debugMessage @3 :Text;
-}
diff --git a/src/ipc/capnp/mining.cpp b/src/ipc/capnp/mining.cpp
index 0f9533c1c73..f598f1b2d8e 100644
--- a/src/ipc/capnp/mining.cpp
+++ b/src/ipc/capnp/mining.cpp
@@ -8,40 +8,4 @@
 #include <mp/proxy-types.h>
 
 namespace mp {
-void CustomBuildMessage(InvokeContext& invoke_context,
-                        const BlockValidationState& src,
-                        ipc::capnp::messages::BlockValidationState::Builder&& builder)
-{
-    if (src.IsValid()) {
-        builder.setMode(0);
-    } else if (src.IsInvalid()) {
-        builder.setMode(1);
-    } else if (src.IsError()) {
-        builder.setMode(2);
-    } else {
-        assert(false);
-    }
-    builder.setResult(static_cast<int>(src.GetResult()));
-    builder.setRejectReason(src.GetRejectReason());
-    builder.setDebugMessage(src.GetDebugMessage());
-}
-
-void CustomReadMessage(InvokeContext& invoke_context,
-                       const ipc::capnp::messages::BlockValidationState::Reader& reader,
-                       BlockValidationState& dest)
-{
-    if (reader.getMode() == 0) {
-        assert(reader.getResult() == 0);
-        assert(reader.getRejectReason().size() == 0);
-        assert(reader.getDebugMessage().size() == 0);
-    } else if (reader.getMode() == 1) {
-        dest.Invalid(static_cast<BlockValidationResult>(reader.getResult()), reader.getRejectReason(), reader.getDebugMessage());
-    } else if (reader.getMode() == 2) {
-        assert(reader.getResult() == 0);
-        dest.Error(reader.getRejectReason());
-        assert(reader.getDebugMessage().size() == 0);
-    } else {
-        assert(false);
-    }
-}
 } // namespace mp
diff --git a/src/test/ipc_test.capnp b/src/test/ipc_test.capnp
index 7fd59cf5882..e33f711bf3c 100644
--- a/src/test/ipc_test.capnp
+++ b/src/test/ipc_test.capnp
@@ -19,6 +19,5 @@ interface FooInterface $Proxy.wrap("FooImplementation") {
     passUniValue @2 (arg :Text) -> (result :Text);
     passTransaction @3 (arg :Data) -> (result :Data);
     passVectorChar @4 (arg :Data) -> (result :Data);
-    passBlockState @5 (arg :Mining.BlockValidationState) -> (result :Mining.BlockValidationState);
-    passScript @6 (arg :Data) -> (result :Data);
+    passScript @5 (arg :Data) -> (result :Data);
 }
diff --git a/src/test/ipc_test.cpp b/src/test/ipc_test.cpp
index dd46883fb09..b4d7ad354cc 100644
--- a/src/test/ipc_test.cpp
+++ b/src/test/ipc_test.cpp
@@ -102,25 +102,6 @@ void IpcPipeTest()
     std::vector<char> vec2{foo->passVectorChar(vec1)};
     BOOST_CHECK_EQUAL(std::string_view(vec1.begin(), vec1.end()), std::string_view(vec2.begin(), vec2.end()));
 
-    BlockValidationState bs1;
-    bs1.Invalid(BlockValidationResult::BLOCK_MUTATED, "reject reason", "debug message");
-    BlockValidationState bs2{foo->passBlockState(bs1)};
-    BOOST_CHECK_EQUAL(bs1.IsValid(), bs2.IsValid());
-    BOOST_CHECK_EQUAL(bs1.IsError(), bs2.IsError());
-    BOOST_CHECK_EQUAL(bs1.IsInvalid(), bs2.IsInvalid());
-    BOOST_CHECK_EQUAL(static_cast<int>(bs1.GetResult()), static_cast<int>(bs2.GetResult()));
-    BOOST_CHECK_EQUAL(bs1.GetRejectReason(), bs2.GetRejectReason());
-    BOOST_CHECK_EQUAL(bs1.GetDebugMessage(), bs2.GetDebugMessage());
-
-    BlockValidationState bs3;
-    BlockValidationState bs4{foo->passBlockState(bs3)};
-    BOOST_CHECK_EQUAL(bs3.IsValid(), bs4.IsValid());
-    BOOST_CHECK_EQUAL(bs3.IsError(), bs4.IsError());
-    BOOST_CHECK_EQUAL(bs3.IsInvalid(), bs4.IsInvalid());
-    BOOST_CHECK_EQUAL(static_cast<int>(bs3.GetResult()), static_cast<int>(bs4.GetResult()));
-    BOOST_CHECK_EQUAL(bs3.GetRejectReason(), bs4.GetRejectReason());
-    BOOST_CHECK_EQUAL(bs3.GetDebugMessage(), bs4.GetDebugMessage());
-
     auto script1{CScript() << OP_11};
     auto script2{foo->passScript(script1)};
     BOOST_CHECK_EQUAL(HexStr(script1), HexStr(script2));