diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index d8e626ad..69ea3514 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,4 +1,4 @@
 {
-    "tket2-py": "0.3.0",
+    "tket2-py": "0.4.0",
     "tket2-eccs": "0.1.0"
 }
\ No newline at end of file
diff --git a/tket2-py/CHANGELOG.md b/tket2-py/CHANGELOG.md
index 4d36bc06..3f0a3d34 100644
--- a/tket2-py/CHANGELOG.md
+++ b/tket2-py/CHANGELOG.md
@@ -1,5 +1,46 @@
 # Changelog
 
+## [0.4.0](https://github.com/CQCL/tket2/compare/tket2-py-v0.3.0...tket2-py-v0.4.0) (2024-10-01)
+
+
+### ⚠ BREAKING CHANGES
+
+* Made all errors `non_exhaustive`, and renamed some fields for clarity.
+* "tket2.angle" extension replaced with "tket2.rotation" extension with rotation type and simplified set of operations.
+* TryFrom implementations for extension op structs removed, use `cast`
+* quantum extension renamed from "quantum.tket2" to "tket2.quantum"
+* Parametric Tk2Ops take angle type rather than float.
+* Rename lazy extension to "hseries" and add hseries ops.
+* `Tk2Op::AngleAdd` removed, use `fadd` from the hugr float ops standard extension
+* Updated to latest hugr version (`hugr-rs 0.12` / `hugr-py 0.8`). ECCs need to be recompiled.
+
+### Features
+
+* HSeries ops ([#573](https://github.com/CQCL/tket2/issues/573)) ([e6acc88](https://github.com/CQCL/tket2/commit/e6acc881d7ab67c584e6622d387bf2025209f8b8))
+* remove Tk2Op::AngleAdd ([#567](https://github.com/CQCL/tket2/issues/567)) ([42cc82f](https://github.com/CQCL/tket2/commit/42cc82f0ee6e77dffb2f55c53613a7c4c8687824))
+* replace f64 with angle type for tk2 ops ([#578](https://github.com/CQCL/tket2/issues/578)) ([d14631f](https://github.com/CQCL/tket2/commit/d14631f762f7ad2cf7db65e66b11cc38a54966ef))
+* simplify angle extension in to a half turns rotation type ([#611](https://github.com/CQCL/tket2/issues/611)) ([0723937](https://github.com/CQCL/tket2/commit/0723937a8aed69302359fbd2383a01a77adc6b36))
+* Support encoding float and sympy ops ([#618](https://github.com/CQCL/tket2/issues/618)) ([74dcbf7](https://github.com/CQCL/tket2/commit/74dcbf757c1c2ae57bf313c61296df270167ee7d))
+* **tket2-hseries:** cli extension dumping ([#584](https://github.com/CQCL/tket2/issues/584)) ([abf292f](https://github.com/CQCL/tket2/commit/abf292f82b858840eeb067394105dbc62feb3230))
+* Update rust hugr dependency to `0.12.0`, and python hugr to `0.8.0` ([#568](https://github.com/CQCL/tket2/issues/568)) ([258a7c5](https://github.com/CQCL/tket2/commit/258a7c5ec25ee2665c524a174704944f0c19729e))
+
+
+### Bug Fixes
+
+* quantum extension name wrong way round ([#582](https://github.com/CQCL/tket2/issues/582)) ([06a6838](https://github.com/CQCL/tket2/commit/06a68386ce6d0b1376ed369da2a42d3b3eaa056a))
+* remove TryFrom for extension ops use `cast` ([#592](https://github.com/CQCL/tket2/issues/592)) ([5ca29af](https://github.com/CQCL/tket2/commit/5ca29af3a7cc6ce6d8b3261b342015da94f4aab0))
+* Support hugr packages, fix the notebooks ([#622](https://github.com/CQCL/tket2/issues/622)) ([1cf9dcb](https://github.com/CQCL/tket2/commit/1cf9dcb7ba80dd236916bcf86a1fa0f5459fd349))
+
+
+### Documentation
+
+* Add tket2-py module docstring ([#539](https://github.com/CQCL/tket2/issues/539)) ([8ef7a57](https://github.com/CQCL/tket2/commit/8ef7a5736294cf462b0694c235f0d10316c68f68))
+
+
+### Miscellaneous Chores
+
+* Replace thiserror with derive_more 1.0 ([#624](https://github.com/CQCL/tket2/issues/624)) ([2250ce7](https://github.com/CQCL/tket2/commit/2250ce76f3019deee1d7e1206aa7843a745fe988))
+
 ## [0.3.0](https://github.com/CQCL/tket2/compare/tket2-py-v0.2.1...tket2-py-v0.3.0) (2024-09-04)
 
 
diff --git a/tket2-py/pyproject.toml b/tket2-py/pyproject.toml
index 6e5af4ff..f4219037 100644
--- a/tket2-py/pyproject.toml
+++ b/tket2-py/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "tket2"
-version = "0.3.0"
+version = "0.4.0"
 requires-python = ">=3.10,<3.13"
 description = "Quantinuum's TKET2 Quantum Compiler"
 license = { file = "LICENCE" }
diff --git a/tket2-py/tket2/__init__.py b/tket2-py/tket2/__init__.py
index ca065ce8..2a2d55a7 100644
--- a/tket2-py/tket2/__init__.py
+++ b/tket2-py/tket2/__init__.py
@@ -16,4 +16,4 @@
 
 # This is updated by our release-please workflow, triggered by this
 # annotation: x-release-please-version
-__version__ = "0.3.0"
+__version__ = "0.4.0"