mongodb · blink1073 · Aug 27, 2026 · Jun 24, 2026 · Jun 24, 2026 · Jun 24, 2026
@@ -134,16 +134,16 @@ buildvariants:
       COMPRESSOR: zlib
   - name: compression-zstd-rhel8
     tasks:
-      - name: .test-standard !.server-4.2
+      - name: .test-standard
     display_name: Compression zstd RHEL8
     run_on:
       - rhel87-small
     expansions:
       COMPRESSOR: zstd
   - name: compression-zstd-ubuntu-22
     tasks:
-      - name: .test-standard !.server-4.2 !.server-4.4 !.server-5.0 .python-3.14
-      - name: .test-standard !.server-4.2 !.server-4.4 !.server-5.0 .python-3.14t
+      - name: .test-standard !.server-4.4 !.server-5.0 .python-3.14
+      - name: .test-standard !.server-4.4 !.server-5.0 .python-3.14t
     display_name: Compression zstd Ubuntu-22
     run_on:
       - ubuntu2204-small
@@ -492,15 +492,6 @@ buildvariants:
       - rhel87-small
 
   # Server version tests
-  - name: mongodb-v4.2
-    tasks:
-      - name: .server-version
-    display_name: "* MongoDB v4.2"
-    run_on:
-      - rhel87-small
-    expansions:
-      VERSION: "4.2"
-    tags: [coverage_tag]
   - name: mongodb-v4.4
     tasks:
       - name: .server-version

@@ -187,10 +187,7 @@ def create_compression_variants():
     variants = []
     for compressor in "snappy", "zlib", "zstd":
         expansions = dict(COMPRESSOR=compressor)
-        if compressor == "zstd":
-            tasks = [".test-standard !.server-4.2"]
-        else:
-            tasks = [".test-standard"]
+        tasks = [".test-standard"]
         display_name = get_variant_name(f"Compression {compressor}", host)
         variants.append(
             create_variant(
@@ -204,8 +201,8 @@ def create_compression_variants():
     host = HOSTS["ubuntu22"]
     expansions = dict(COMPRESSOR="ztsd")
     tasks = [
-        ".test-standard !.server-4.2 !.server-4.4 !.server-5.0 .python-3.14",
-        ".test-standard !.server-4.2 !.server-4.4 !.server-5.0 .python-3.14t",
+        ".test-standard !.server-4.4 !.server-5.0 .python-3.14",
+        ".test-standard !.server-4.4 !.server-5.0 .python-3.14t",
     ]
     display_name = get_variant_name(f"Compression {compressor}", host)
     variants.append(

@@ -21,7 +21,7 @@
 # Globals
 ##############
 
-ALL_VERSIONS = ["4.2", "4.4", "5.0", "6.0", "7.0", "8.0", "9.0", "rapid", "latest"]
+ALL_VERSIONS = ["4.4", "5.0", "6.0", "7.0", "8.0", "9.0", "rapid", "latest"]
 CPYTHONS = ["3.10", "3.11", "3.12", "3.13", "3.14t", "3.14"]
 PYPYS = ["pypy3.11"]
 MIN_SUPPORT_VERSIONS = ["3.9", "pypy3.9", "pypy3.10"]

@@ -3,6 +3,7 @@
 set -eu
 
 HERE=$(dirname ${BASH_SOURCE:-$0})
+HERE="$( cd -- "$HERE" > /dev/null 2>&1 && pwd )"
 pushd "$(dirname "$(dirname $HERE)")" > /dev/null
 
 # Source the env files to pick up common variables.

@@ -22,6 +22,12 @@ fi
 # Ensure dependencies are installed.
 bash $HERE/install-dependencies.sh
 
+# Re-source env.sh: install-dependencies.sh may have appended to it, e.g. when it
+# had to install Python on an image that lacks a toolchain.
+if [ -f $HERE/env.sh ]; then
+  . $HERE/env.sh
+fi
+
 # Add the default install path to the path if needed.
 if [ -z "${PYMONGO_BIN_DIR:-}" ]; then
   export PATH="$PATH:$HOME/.local/bin"

@@ -41,9 +41,16 @@ if [ -z "${UV_PYTHON:-}" ]; then
           _exe="python.exe"
         fi
         if [ -n "${IS_WIN32:-}" ]; then
-            _python="C:/python/32/Python${_python}/${_exe}"
+            _win_python="C:/python/32/Python${_python}/${_exe}"
         else
-            _python="C:/python/Python${_python}/${_exe}"
+            _win_python="C:/python/Python${_python}/${_exe}"
+        fi
+        # Fall back to the version string if the toolchain path doesn't exist.
+        # uv will then download and manage Python itself.
+        if [ -f "$_win_python" ]; then
+            _python="$_win_python"
+        else
+            _python="$TOOLCHAIN_VERSION"
         fi
     elif [ -d "/opt/python/$_python/bin" ]; then
         _python="/opt/python/$_python/bin/python3"

@@ -273,6 +273,7 @@ def handle_test_env() -> None:
         write_env("GSSAPI_HOST", config["SASL_HOST"])
         write_env("GSSAPI_PORT", config["SASL_PORT"])
         write_env("GSSAPI_PRINCIPAL", config["PRINCIPAL"])
+        write_env("SASL_HOST", config["SASL_HOST"])
 
     if test_name == "doctest":
         UV_ARGS.append("--extra docs")

@@ -15,7 +15,7 @@ a native Python driver for MongoDB, offering both synchronous and asynchronous A
 [gridfs](https://github.com/mongodb/specifications/blob/master/source/gridfs/gridfs-spec.md/)
 implementation on top of `pymongo`.
 
-PyMongo supports MongoDB 4.0, 4.2, 4.4, 5.0, 6.0, 7.0, and 8.0. PyMongo follows [semantic versioning](https://semver.org/spec/v2.0.0.html) for its releases.
+PyMongo supports MongoDB 4.4, 5.0, 6.0, 7.0, 8.0, and 9.0. PyMongo follows [semantic versioning](https://semver.org/spec/v2.0.0.html) for its releases.
 
 ## Documentation
 

@@ -6,6 +6,7 @@ Changes in Version 4.18.0 (2026/XX/XX)
 
 PyMongo 4.18 brings a number of changes including:
 
+- Dropped support for MongoDB 4.2.
 - Added support for MongoDB 9.0.
 - Improved TLS connection performance by reusing TLS sessions across connections
   to the same server, avoiding a full handshake on each new connection.

@@ -53,7 +53,7 @@ def __init__(
         options: MutableMapping[str, Any],
         let: Optional[Mapping[str, Any]] = None,
         user_fields: Optional[MutableMapping[str, Any]] = None,
-        result_processor: Optional[Callable[[Mapping[str, Any], AsyncConnection], None]] = None,
+        result_processor: Optional[Callable[[Mapping[str, Any]], None]] = None,
         comment: Any = None,
     ) -> None:
         if "explain" in options:
@@ -145,13 +145,8 @@ async def get_cursor(
         cmd = {"aggregate": self._aggregation_target, "pipeline": self._pipeline}
         cmd.update(self._options)
 
-        # Apply this target's read concern if:
-        # readConcern has not been specified as a kwarg and either
-        # - server version is >= 4.2 or
-        # - server version is >= 3.2 and pipeline doesn't use $out
-        if ("readConcern" not in cmd) and (
-            not self._performs_write or (conn.max_wire_version >= 8)
-        ):
+        # $out/$merge pipelines also support readConcern on all supported server versions (4.4+).
+        if "readConcern" not in cmd:
             read_concern = self._target.read_concern
         else:
             read_concern = None
@@ -180,7 +175,7 @@ async def get_cursor(
         )
 
         if self._result_processor:
-            self._result_processor(result, conn)
+            self._result_processor(result)
 
         # Extract cursor from result or mock/fake one if necessary.
         if "cursor" in result:

@@ -343,20 +343,17 @@ async def _authenticate_x509(credentials: MongoCredential, conn: AsyncConnection
 
 
 async def _authenticate_default(credentials: MongoCredential, conn: AsyncConnection) -> None:
-    if conn.max_wire_version >= 7:
-        if conn.negotiated_mechs:
-            mechs = conn.negotiated_mechs
-        else:
-            source = credentials.source
-            cmd = conn.hello_cmd()
-            cmd["saslSupportedMechs"] = source + "." + credentials.username
-            mechs = (await conn.command(source, cmd, publish_events=False)).get(
-                "saslSupportedMechs", []
-            )
-        if "SCRAM-SHA-256" in mechs:
-            return await _authenticate_scram(credentials, conn, "SCRAM-SHA-256")
-        else:
-            return await _authenticate_scram(credentials, conn, "SCRAM-SHA-1")
+    if conn.negotiated_mechs:
+        mechs = conn.negotiated_mechs
+    else:
+        source = credentials.source
+        cmd = conn.hello_cmd()
+        cmd["saslSupportedMechs"] = source + "." + credentials.username
+        mechs = (await conn.command(source, cmd, publish_events=False)).get(
+            "saslSupportedMechs", []
+        )
+    if "SCRAM-SHA-256" in mechs:
+        return await _authenticate_scram(credentials, conn, "SCRAM-SHA-256")
     else:
         return await _authenticate_scram(credentials, conn, "SCRAM-SHA-1")
 

@@ -48,9 +48,6 @@ async def _authenticate_aws(credentials: MongoCredential, conn: AsyncConnection)
 
     set_use_cached_credentials(True)
 
-    if conn.max_wire_version < 9:
-        raise ConfigurationError("MONGODB-AWS authentication requires MongoDB version 4.4 or later")
-
     class AwsSaslContext(pymongo_auth_aws.AwsSaslContext):  # type: ignore
         # Dependency injection:
         def binary_type(self) -> type[Binary]:

@@ -102,8 +102,6 @@ def __init__(
         self.bypass_doc_val = bypass_document_validation
         self.uses_collation = False
         self.uses_array_filters = False
-        self.uses_hint_update = False
-        self.uses_hint_delete = False
         self.uses_sort = False
         self.is_retryable = True
         self.retrying = False
@@ -154,7 +152,6 @@ def add_update(
             self.uses_array_filters = True
             cmd["arrayFilters"] = array_filters
         if hint is not None:
-            self.uses_hint_update = True
             cmd["hint"] = hint
         if sort is not None:
             self.uses_sort = True
@@ -182,7 +179,6 @@ def add_replace(
             self.uses_collation = True
             cmd["collation"] = collation
         if hint is not None:
-            self.uses_hint_update = True
             cmd["hint"] = hint
         if sort is not None:
             self.uses_sort = True
@@ -202,7 +198,6 @@ def add_delete(
             self.uses_collation = True
             cmd["collation"] = collation
         if hint is not None:
-            self.uses_hint_delete = True
             cmd["hint"] = hint
         if limit == _DELETE_ALL:
             # A bulk_write containing a delete_many is not retryable.
@@ -572,14 +567,6 @@ async def execute_no_results(
             raise ConfigurationError("arrayFilters is unsupported for unacknowledged writes.")
         # Guard against unsupported unacknowledged writes.
         unack = write_concern and not write_concern.acknowledged
-        if unack and self.uses_hint_delete and conn.max_wire_version < 9:
-            raise ConfigurationError(
-                "Must be connected to MongoDB 4.4+ to use hint on unacknowledged delete commands."
-            )
-        if unack and self.uses_hint_update and conn.max_wire_version < 8:
-            raise ConfigurationError(
-                "Must be connected to MongoDB 4.2+ to use hint on unacknowledged update commands."
-            )
         if unack and self.uses_sort and conn.max_wire_version < 25:
             raise ConfigurationError(
                 "Must be connected to MongoDB 8.0+ to use sort on unacknowledged update commands."

@@ -43,49 +43,19 @@
 
 _IS_SYNC = False
 
-# The change streams spec considers the following server errors from the
-# getMore command non-resumable. All other getMore errors are resumable.
-_RESUMABLE_GETMORE_ERRORS = frozenset(
-    [
-        6,  # HostUnreachable
-        7,  # HostNotFound
-        89,  # NetworkTimeout
-        91,  # ShutdownInProgress
-        189,  # PrimarySteppedDown
-        262,  # ExceededTimeLimit
-        9001,  # SocketException
-        10107,  # NotWritablePrimary
-        11600,  # InterruptedAtShutdown
-        11602,  # InterruptedDueToReplStateChange
-        13435,  # NotPrimaryNoSecondaryOk
-        13436,  # NotPrimaryOrSecondary
-        63,  # StaleShardVersion
-        150,  # StaleEpoch
-        13388,  # StaleConfig
-        234,  # RetryChangeStream
-        133,  # FailedToSatisfyReadPreference
-    ]
-)
-
-
 if TYPE_CHECKING:
     from pymongo.asynchronous.client_session import AsyncClientSession
     from pymongo.asynchronous.collection import AsyncCollection
     from pymongo.asynchronous.database import AsyncDatabase
     from pymongo.asynchronous.mongo_client import AsyncMongoClient
-    from pymongo.asynchronous.pool import AsyncConnection
 
 
 def _resumable(exc: PyMongoError) -> bool:
     """Return True if given a resumable change stream error."""
     if isinstance(exc, (ConnectionFailure, CursorNotFound)):
         return True
     if isinstance(exc, OperationFailure):
-        if exc._max_wire_version is None:
-            return False
-        return (
-            exc._max_wire_version >= 9 and exc.has_error_label("ResumableChangeStreamError")
-        ) or (exc._max_wire_version < 9 and exc.code in _RESUMABLE_GETMORE_ERRORS)
+        return exc.has_error_label("ResumableChangeStreamError")
     return False
 
 
@@ -212,13 +182,10 @@ def _aggregation_pipeline(self) -> list[dict[str, Any]]:
         full_pipeline.extend(self._pipeline)
         return full_pipeline
 
-    def _process_result(self, result: Mapping[str, Any], conn: AsyncConnection) -> None:
+    def _process_result(self, result: Mapping[str, Any]) -> None:
         """Callback that caches the postBatchResumeToken or
         startAtOperationTime from a changeStream aggregate command response
         containing an empty batch of change documents.
-
-        This is implemented as a callback because we need access to the wire
-        version in order to determine whether to cache this value.
         """
         if not result["cursor"]["firstBatch"]:
             if "postBatchResumeToken" in result["cursor"]:
@@ -227,7 +194,6 @@ def _process_result(self, result: Mapping[str, Any], conn: AsyncConnection) -> N
                 self._start_at_operation_time is None
                 and self._uses_resume_after is False
                 and self._uses_start_after is False
-                and conn.max_wire_version >= 7
             ):
                 self._start_at_operation_time = result.get("operationTime")
                 # PYTHON-2181: informative error on missing operationTime.