diff --git a/test/functional/interface_ipc_mining.py b/test/functional/interface_ipc_mining.py
index 6f2237a883d..0c3b9cf869c 100755
--- a/test/functional/interface_ipc_mining.py
+++ b/test/functional/interface_ipc_mining.py
@@ -7,7 +7,6 @@ import asyncio
 import time
 from contextlib import AsyncExitStack
 from io import BytesIO
-import platform
 from test_framework.blocktools import NULL_OUTPOINT
 from test_framework.messages import (
     MAX_BLOCK_WEIGHT,
@@ -42,6 +41,7 @@ from test_framework.ipc_util import (
     mining_wait_next_template,
     wait_and_do,
     make_mining_ctx,
+    assert_capnp_failed
 )
 
 # Test may be skipped and not have capnp installed
@@ -325,15 +325,7 @@ class IPCMiningTest(BitcoinTestFramework):
                 await mining.createNewBlock(ctx, opts)
                 raise AssertionError("createNewBlock unexpectedly succeeded")
             except capnp.lib.capnp.KjException as e:
-                if e.description == "remote exception: unknown non-KJ exception of type: kj::Exception":
-                    # macOS + REDUCE_EXPORTS bug: Cap'n Proto fails to recognize
-                    # its own exception type and returns a generic error instead.
-                    # https://github.com/bitcoin/bitcoin/pull/34422#discussion_r2863852691
-                    # Assert this only occurs on Darwin until fixed.
-                    assert_equal(platform.system(), "Darwin")
-                else:
-                    assert_equal(e.description, "remote exception: std::exception: block_reserved_weight (0) must be at least 2000 weight units")
-                assert_equal(e.type, "FAILED")
+                assert_capnp_failed(e, "remote exception: std::exception: block_reserved_weight (0) must be at least 2000 weight units")
 
         asyncio.run(capnp.run(async_routine()))
 
@@ -357,6 +349,13 @@ class IPCMiningTest(BitcoinTestFramework):
                 block.hashMerkleRoot = block.calc_merkle_root()
                 original_version = block.nVersion
 
+                self.log.debug("Submit solution that can't be deserialized")
+                try:
+                    await template.submitSolution(ctx, 0, 0, 0, b"")
+                    raise AssertionError("submitSolution unexpectedly succeeded")
+                except capnp.lib.capnp.KjException as e:
+                    assert_capnp_failed(e, "remote exception: std::exception: SpanReader::read(): end of data:")
+
                 self.log.debug("Submit a block with a bad version")
                 block.nVersion = 0
                 block.solve()
diff --git a/test/functional/test_framework/ipc_util.py b/test/functional/test_framework/ipc_util.py
index c80f78f79b7..03e3b5d511b 100644
--- a/test/functional/test_framework/ipc_util.py
+++ b/test/functional/test_framework/ipc_util.py
@@ -10,9 +10,13 @@ from dataclasses import dataclass
 from io import BytesIO
 from pathlib import Path
 import shutil
+import platform
 from typing import Optional
 
 from test_framework.messages import CBlock
+from test_framework.util import (
+    assert_equal
+)
 
 # Test may be skipped and not have capnp installed
 try:
@@ -155,3 +159,14 @@ async def make_mining_ctx(self):
     self.log.debug("Create Mining proxy object")
     mining = init.makeMining(ctx).result
     return ctx, mining
+
+def assert_capnp_failed(e, description_prefix):
+    if e.description == "remote exception: unknown non-KJ exception of type: kj::Exception":
+        # macOS + REDUCE_EXPORTS bug: Cap'n Proto fails to recognize
+        # its own exception type and returns a generic error instead.
+        # https://github.com/bitcoin/bitcoin/pull/34422#discussion_r2863852691
+        # Assert this only occurs on Darwin until fixed.
+        assert_equal(platform.system(), "Darwin")
+    else:
+        assert e.description.startswith(description_prefix), f"Expected description starting with '{description_prefix}', got '{e.description}'"
+    assert_equal(e.type, "FAILED")