diff --git a/api/CMakeLists.txt b/api/CMakeLists.txt
index 8d61d1cd1..4777e7cd7 100644
--- a/api/CMakeLists.txt
+++ b/api/CMakeLists.txt
@@ -21,6 +21,10 @@ c4_log("found swig ${SWIG_VERSION}: ${SWIG_EXECUTABLE}")
 # https://cmake.org/cmake/help/v3.13/module/UseSWIG.html
 include(UseSWIG)
 
+if(NOT RYML_DEFAULT_CALLBACK_USES_EXCEPTIONS)
+    message(FATAL_ERROR "API requires exceptions")
+endif()
+
 set(RYML_API_DIR ${CMAKE_CURRENT_LIST_DIR})
 set(RYML_SWIG_SRC ${RYML_API_DIR}/ryml.i)
 
@@ -99,7 +103,8 @@ if(RYML_BUILD_API_PYTHON)
     if(WIN32)
         target_compile_definitions(${t} PUBLIC __WIN32__)
     endif()
-    target_compile_definitions(${t} PUBLIC ${RYML_SWIG_ARCH_DEFINES})
+    c4_get_transitive_property(ryml COMPILE_DEFINITIONS ryml_defs)
+    target_compile_definitions(${t} PUBLIC ${RYML_SWIG_ARCH_DEFINES} ${ryml_defs})
 
     # Install the SWIG .so/.dll file
     install(
diff --git a/api/python/Makefile b/api/python/Makefile
index bdb5a6ffd..4f79f02fd 100644
--- a/api/python/Makefile
+++ b/api/python/Makefile
@@ -13,7 +13,7 @@ endif
 # How to invoke python
 PYTHON := python
 # How to invoke pytest
-PYTEST := $(PYTHON) -m pytest -vvv
+PYTEST := $(PYTHON) -m pytest -vvv -s
 
 ACTIVATE=[[ -e $(ACTIVATE_SCRIPT) ]] && source $(ACTIVATE_SCRIPT);
 
@@ -40,10 +40,11 @@ venv:
 	# Setup requirements.
 	${ACTIVATE} pip install -v -r requirements.txt
 	${ACTIVATE} pip install -v -e ../..
-	@${ACTIVATE} $(PYTHON) -c "from ryml.version import version as v; print('Installed version:', v)"
+	${ACTIVATE} $(PYTHON) -c "from ryml.version import version as v; print('Installed version:', v)"
 
 .PHONY: build-sdist
 build-sdist: | $(ACTIVATE_SCRIPT)
+	${ACTIVATE} (cd ../..; pip show build)
 	${ACTIVATE} (cd ../..; $(PYTHON) -m build --sdist --outdir $(PWD)/dist)
 
 
@@ -55,30 +56,27 @@ build-wheel: | $(ACTIVATE_SCRIPT)
 	${ACTIVATE} pip wheel -v dist/*.tar.gz --wheel-dir $(PWD)/dist
 
 .PHONY: build
-build:
-	rm -rf build dist
-	$(MAKE) build-sdist
-	$(MAKE) build-wheel
+build: build-sdist build-wheel
 
 # PYPI_TEST = --repository-url https://test.pypi.org/legacy/
 PYPI_TEST = --repository testpypi
 
 .PHONY: upload-test
 upload-test: | $(ACTIVATE_SCRIPT)
-	make clean
-	make build-sdist
+	$(MAKE) clean
+	$(MAKE) build-sdist
 	${ACTIVATE} twine upload ${PYPI_TEST} dist/*
 
 .PHONY: upload
 upload: | $(ACTIVATE_SCRIPT)
-	make clean
-	make build-sdist
+	$(MAKE) clean
+	$(MAKE) build-sdist
 	${ACTIVATE} twine upload --verbose dist/*
 
 .PHONY: check
 check: | $(ACTIVATE_SCRIPT)
-	make clean
-	make build-wheel
+	$(MAKE) clean
+	$(MAKE) build-wheel
 	${ACTIVATE} twine check dist/*.whl
 
 .PHONY: install
@@ -87,6 +85,7 @@ install: | $(ACTIVATE_SCRIPT)
 
 .PHONY: test
 test: | $(ACTIVATE_SCRIPT)
+	${ACTIVATE} pip install -v -e ../..
 	${ACTIVATE} $(PYTEST) tests
 
 .PHONY: version
diff --git a/api/python/requirements.txt b/api/python/requirements.txt
index 86c126420..4a902dfd8 100644
--- a/api/python/requirements.txt
+++ b/api/python/requirements.txt
@@ -3,3 +3,5 @@ ninja
 pyyaml
 prettytable
 pytest
+build
+twine
diff --git a/api/python/tests/test_parse.py b/api/python/tests/test_parse.py
index bb7973cb3..4f3ae98fa 100644
--- a/api/python/tests/test_parse.py
+++ b/api/python/tests/test_parse.py
@@ -481,6 +481,30 @@ def test44_emit_json_short_buf(self):
 
 
 
+# -----------------------------------------------------------------------------
+# -----------------------------------------------------------------------------
+# -----------------------------------------------------------------------------
+
+class TestParseFailure(unittest.TestCase):
+
+    yaml = "[:HELLO: b}"
+
+    def setUp(self):
+        self.src_as_str = str(__class__.yaml)
+        self.src_as_bytearray = bytearray(__class__.yaml, "utf8")
+
+    def test_in_arena(self):
+        self.assertNotEqual(self.src_as_str, "")
+        with self.assertRaises(RuntimeError):
+            tree = ryml.parse_in_arena(self.src_as_str)
+
+    def test_in_place(self):
+        self.assertNotEqual(self.src_as_bytearray, "")
+        with self.assertRaises(RuntimeError):
+            tree = ryml.parse_in_place(self.src_as_bytearray)
+
+
+
 # -----------------------------------------------------------------------------
 # -----------------------------------------------------------------------------
 # -----------------------------------------------------------------------------
diff --git a/api/ryml.i b/api/ryml.i
index ac226142a..c4f832fd0 100644
--- a/api/ryml.i
+++ b/api/ryml.i
@@ -1,7 +1,6 @@
 
 %module ryml
 
-
 //-----------------------------------------------------------------------------
 // this block will be pasted verbatim in the generated C++ source file
 
@@ -23,8 +22,8 @@ using csubstr = c4::csubstr;
 
 %}
 
-//-----------------------------------------------------------------------------
 
+//-----------------------------------------------------------------------------
 
 %apply (const char *STRING, size_t LENGTH) { (const char *str, size_t len) };
 %apply (char *STRING, size_t LENGTH) { (char *str, size_t len) };
@@ -91,6 +90,8 @@ using csubstr = c4::csubstr;
 %typemap(typecheck) c4::csubstr = const char *;
 
 
+//-----------------------------------------------------------------------------
+
 %typemap(out) c4::csubstr {
 #if defined(SWIGPYTHON)
   if($1.str == nullptr) {
@@ -111,6 +112,26 @@ using csubstr = c4::csubstr;
 };
 
 
+//-----------------------------------------------------------------------------
+
+// Language independent exception handler.
+// KEEP THIS BEFORE THE FOLLOWING FUNCTIONS!
+// see https://stackoverflow.com/a/61621747
+%include <std_string.i>
+%include <exception.i>
+%exception {
+    try {
+        $action
+    } catch(std::exception &e) {
+        SWIG_exception(SWIG_RuntimeError, e.what());
+    } catch(...) {
+        SWIG_exception(SWIG_UnknownError, "unknown error");
+    }
+}
+
+
+//-----------------------------------------------------------------------------
+
 %inline %{
 
 void parse_csubstr(c4::csubstr s, c4::yml::Tree *t)
diff --git a/doc/sphinx_other_languages.rst b/doc/sphinx_other_languages.rst
index 3c0cefdf9..f9dc9c909 100644
--- a/doc/sphinx_other_languages.rst
+++ b/doc/sphinx_other_languages.rst
@@ -25,6 +25,7 @@ using `emscripten`:
       -D RYML_BUILD_TESTS=ON \
       -D RYML_BUILD_BENCHMARKS=OFF \
       -D RYML_TEST_SUITE=OFF \
+      -D RYML_DEFAULT_CALLBACK_USES_EXCEPTIONS=ON \
       -D CMAKE_BUILD_TYPE=Release \
       -D CMAKE_CXX_FLAGS='-s DISABLE_EXCEPTION_CATCHING=0'
    cmake --build build/emscripten --target ryml-test-run -j
diff --git a/setup.py b/setup.py
index c604758f4..3f56a87f0 100644
--- a/setup.py
+++ b/setup.py
@@ -56,6 +56,8 @@ def get_environment_cmake_flags():
     cmake_component='python',
     cmake_configure_options=get_environment_cmake_flags() + [
         "-DRYML_BUILD_API:BOOL=ON",
+        "-DRYML_DEFAULT_CALLBACKS:BOOL=ON",
+        "-DRYML_DEFAULT_CALLBACK_USES_EXCEPTIONS:BOOL=ON",
         # Force cmake to use the Python interpreter we are currently
         # using to run setup.py
         "-DPython3_EXECUTABLE:FILEPATH=" + sys.executable,
diff --git a/src/c4/yml/common.cpp b/src/c4/yml/common.cpp
index 56758e3eb..cdfdb81b8 100644
--- a/src/c4/yml/common.cpp
+++ b/src/c4/yml/common.cpp
@@ -8,6 +8,7 @@
 #   endif
 #endif // RYML_NO_DEFAULT_CALLBACKS
 
+
 namespace c4 {
 namespace yml {