diff --git a/.github/workflows/release-python.yml b/.github/workflows/release-python.yml
index 9cce310d91..cbb2322fe8 100644
--- a/.github/workflows/release-python.yml
+++ b/.github/workflows/release-python.yml
@@ -16,7 +16,7 @@ env:
   # Changes per repo
   PRODUCT_NAME: PyMongo
   # Changes per branch
-  EVERGREEN_PROJECT: mongo-python-driver
+  EVERGREEN_PROJECT: mongo-python-driver-release
   # Constant
   # inputs will be empty on a scheduled run.  so, we only set dry_run
   # to 'false' when the input is set to 'false'.
diff --git a/doc/changelog.rst b/doc/changelog.rst
index 64c61e5877..cf84843eb7 100644
--- a/doc/changelog.rst
+++ b/doc/changelog.rst
@@ -1,6 +1,24 @@
 Changelog
 =========
 
+Changes in Version 4.15.1 (2025/09/11)
+--------------------------------------
+
+Version 4.15.1 is a bug fix release.
+
+ - Fixed a bug in :meth:`~pymongo.synchronous.encryption.ClientEncryption.encrypt` and :meth:`~pymongo.asynchronous.encryption.AsyncClientEncryption.encrypt`
+   that would cause a ``TypeError`` when using ``pymongocrypt<1.16`` by passing an unsupported ``type_opts`` parameter even if
+   Queryable Encryption text queries beta was not used.
+
+Issues Resolved
+...............
+
+See the `PyMongo 4.15.1 release notes in JIRA`_ for the list of resolved issues
+in this release.
+
+.. _PyMongo 4.15.1 release notes in JIRA: https://jira.mongodb.org/secure/ReleaseNote.jspa?projectId=10004&version=46486
+
+
 Changes in Version 4.15.0 (2025/09/10)
 --------------------------------------
 
diff --git a/pymongo/_version.py b/pymongo/_version.py
index c6ba82ab13..7abecf4416 100644
--- a/pymongo/_version.py
+++ b/pymongo/_version.py
@@ -18,7 +18,7 @@
 import re
 from typing import List, Tuple, Union
 
-__version__ = "4.16.0.dev0"
+__version__ = "4.15.1"
 
 
 def get_version_tuple(version: str) -> Tuple[Union[int, str], ...]:
diff --git a/pymongo/asynchronous/encryption.py b/pymongo/asynchronous/encryption.py
index b302631108..662f2abd5b 100644
--- a/pymongo/asynchronous/encryption.py
+++ b/pymongo/asynchronous/encryption.py
@@ -935,7 +935,8 @@ async def _encrypt_helper(
                 contention_factor=contention_factor,
                 range_opts=range_opts_bytes,
                 is_expression=is_expression,
-                text_opts=text_opts_bytes,
+                # For compatibility with pymongocrypt < 1.16:
+                **{"text_opts": text_opts_bytes} if text_opts_bytes else {},
             )
             return decode(encrypted_doc)["v"]
 
diff --git a/pymongo/synchronous/encryption.py b/pymongo/synchronous/encryption.py
index 752026af84..518a16ff2d 100644
--- a/pymongo/synchronous/encryption.py
+++ b/pymongo/synchronous/encryption.py
@@ -928,7 +928,8 @@ def _encrypt_helper(
                 contention_factor=contention_factor,
                 range_opts=range_opts_bytes,
                 is_expression=is_expression,
-                text_opts=text_opts_bytes,
+                # For compatibility with pymongocrypt < 1.16:
+                **{"text_opts": text_opts_bytes} if text_opts_bytes else {},
             )
             return decode(encrypted_doc)["v"]