diff --git a/.release-please-manifest.json b/.release-please-manifest.json
index 048d674e..8cce2b69 100644
--- a/.release-please-manifest.json
+++ b/.release-please-manifest.json
@@ -1,3 +1,3 @@
 {
-  ".": "9.12.0"
+  ".": "9.12.1"
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 99d064e7..e2623a1e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,13 @@
 
 All notable changes to the LaunchDarkly Python SDK will be documented in this file. This project adheres to [Semantic Versioning](http://semver.org).
 
+## [9.12.1](https://github.com/launchdarkly/python-server-sdk/compare/9.12.0...9.12.1) (2025-09-30)
+
+
+### Bug Fixes
+
+* Add validation format check for SDK key ([#351](https://github.com/launchdarkly/python-server-sdk/issues/351))
+
 ## [9.12.0](https://github.com/launchdarkly/python-server-sdk/compare/9.11.1...9.12.0) (2025-07-11)
 
 
diff --git a/PROVENANCE.md b/PROVENANCE.md
index 4b23688b..58993a05 100644
--- a/PROVENANCE.md
+++ b/PROVENANCE.md
@@ -9,7 +9,7 @@ To verify SLSA provenance attestations, we recommend using [slsa-verifier](https
 <!-- x-release-please-start-version -->
 ```
 # Set the version of the SDK to verify
-SDK_VERSION=9.12.0
+SDK_VERSION=9.12.1
 ```
 <!-- x-release-please-end -->
 
diff --git a/ldclient/version.py b/ldclient/version.py
index 5440358f..886c2d0d 100644
--- a/ldclient/version.py
+++ b/ldclient/version.py
@@ -1 +1 @@
-VERSION = "9.12.0"  # x-release-please-version
+VERSION = "9.12.1"  # x-release-please-version
diff --git a/pyproject.toml b/pyproject.toml
index 1f149bd3..1371d3c3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "launchdarkly-server-sdk"
-version = "9.12.0"
+version = "9.12.1"
 description = "LaunchDarkly SDK for Python"
 authors = ["LaunchDarkly <dev@launchdarkly.com>"]
 license = "Apache-2.0"