diff --git a/ddtrace/internal/_encoding.pyx b/ddtrace/internal/_encoding.pyx
index f85fe7c6776..600e5a7d751 100644
--- a/ddtrace/internal/_encoding.pyx
+++ b/ddtrace/internal/_encoding.pyx
@@ -8,7 +8,7 @@ import threading
 from json import dumps as json_dumps
 
 from ._utils cimport PyBytesLike_Check
-
+import traceback
 
 # Do not use an absolute import here Cython<3.0.0 will
 #   import `ddtrace.internal.constants` instead when this
@@ -500,7 +500,17 @@ cdef class MsgpackEncoderBase(BufferedEncoder):
             try:
                 ret = self.pack_span(span, dd_origin)
             except Exception as e:
-                raise RuntimeError("failed to pack span: {!r}. Exception: {}".format(span, e))
+                # Capture full traceback information.
+                tb_info = traceback.format_exc()
+                # Safely get the _metrics attribute from span, if available.
+                metrics = getattr(span, "_metrics", None)
+                raise RuntimeError(
+                    "Failed to pack span: {!r}.\n"
+                    "Span metrics: {!r}.\n"
+                    "Exception: {}.\n"
+                    "Traceback:\n{}"
+                    .format(span, metrics, e, tb_info)
+                ) from e
 
             # No exception was raised, but we got an error code from msgpack
             if ret != 0:
diff --git a/tests/tracer/test_encoders.py b/tests/tracer/test_encoders.py
index f96e063502e..e8a7566a320 100644
--- a/tests/tracer/test_encoders.py
+++ b/tests/tracer/test_encoders.py
@@ -799,6 +799,7 @@ def test_encoding_invalid_data(data):
     with pytest.raises(RuntimeError) as e:
         encoder.put(trace)
 
+    # Rachel - these tests will fail
     assert e.match(r"failed to pack span: <Span\(id="), e
     assert encoder.encode()[0] is None