diff --git a/airbyte_cdk/sources/concurrent_source/concurrent_read_processor.py b/airbyte_cdk/sources/concurrent_source/concurrent_read_processor.py
index fa6a568bc..ce06df266 100644
--- a/airbyte_cdk/sources/concurrent_source/concurrent_read_processor.py
+++ b/airbyte_cdk/sources/concurrent_source/concurrent_read_processor.py
@@ -11,6 +11,7 @@
 from airbyte_cdk.sources.concurrent_source.partition_generation_completed_sentinel import (
     PartitionGenerationCompletedSentinel,
 )
+from airbyte_cdk.sources.concurrent_source.stream_abort_registry import StreamAbortRegistry
 from airbyte_cdk.sources.concurrent_source.stream_thread_exception import StreamThreadException
 from airbyte_cdk.sources.concurrent_source.thread_pool_manager import ThreadPoolManager
 from airbyte_cdk.sources.declarative.partition_routers.grouping_partition_router import (
@@ -46,6 +47,7 @@ def __init__(
         message_repository: MessageRepository,
         partition_reader: PartitionReader,
         max_concurrent_partition_generators: Optional[int] = None,
+        stream_abort_registry: Optional[StreamAbortRegistry] = None,
     ):
         """
         This class is responsible for handling items from a concurrent stream read process.
@@ -87,6 +89,7 @@ def __init__(
         self._partition_reader = partition_reader
         self._streams_done: Set[str] = set()
         self._exceptions_per_stream_name: dict[str, List[Exception]] = {}
+        self._stream_abort_registry = stream_abort_registry
 
         # Track which streams (by name) are currently active
         # A stream is "active" if it's generating partitions or has partitions being read
@@ -234,14 +237,24 @@ def on_record(self, record: Record) -> Iterable[AirbyteMessage]:
     def on_exception(self, exception: StreamThreadException) -> Iterable[AirbyteMessage]:
         """
         This method is called when an exception is raised.
-        1. Stop all running streams
-        2. Raise the exception
+        1. Record the exception for the stream
+        2. If the failure is stream-wide (a config error, e.g. an authorization failure that
+           affects every partition), abort the stream so its remaining partitions are skipped
+           instead of repeating the same doomed request.
+        3. Emit a trace message for the exception
         """
         self._flag_exception(exception.stream_name, exception.exception)
         self._logger.exception(
             f"Exception while syncing stream {exception.stream_name}", exc_info=exception.exception
         )
 
+        if self._stream_abort_registry and self._is_stream_wide_failure(exception.exception):
+            self._logger.info(
+                f"Stream {exception.stream_name} failed with a stream-wide error. "
+                f"Skipping its remaining partitions."
+            )
+            self._stream_abort_registry.abort(exception.stream_name)
+
         stream_descriptor = StreamDescriptor(name=exception.stream_name)
         if isinstance(exception.exception, AirbyteTracedException):
             yield exception.exception.as_airbyte_message(stream_descriptor=stream_descriptor)
@@ -255,6 +268,19 @@ def on_exception(self, exception: StreamThreadException) -> Iterable[AirbyteMess
     def _flag_exception(self, stream_name: str, exception: Exception) -> None:
         self._exceptions_per_stream_name.setdefault(stream_name, []).append(exception)
 
+    @staticmethod
+    def _is_stream_wide_failure(exception: Exception) -> bool:
+        """Whether an exception should abort the whole stream rather than just the partition.
+
+        A `config_error` (e.g. 401/403 authorization failures) affects every partition of the
+        stream, so there is no point reading the rest. Other failures (transient server errors,
+        timeouts, etc.) are left as best-effort: the remaining partitions still get a chance.
+        """
+        return (
+            isinstance(exception, AirbyteTracedException)
+            and exception.failure_type == FailureType.config_error
+        )
+
     def start_next_partition_generator(self) -> Optional[AirbyteMessage]:
         """
         Submits the next partition generator to the thread pool.
diff --git a/airbyte_cdk/sources/concurrent_source/concurrent_source.py b/airbyte_cdk/sources/concurrent_source/concurrent_source.py
index 474780bcc..2585cb5d9 100644
--- a/airbyte_cdk/sources/concurrent_source/concurrent_source.py
+++ b/airbyte_cdk/sources/concurrent_source/concurrent_source.py
@@ -12,6 +12,7 @@
 from airbyte_cdk.sources.concurrent_source.partition_generation_completed_sentinel import (
     PartitionGenerationCompletedSentinel,
 )
+from airbyte_cdk.sources.concurrent_source.stream_abort_registry import StreamAbortRegistry
 from airbyte_cdk.sources.concurrent_source.stream_thread_exception import StreamThreadException
 from airbyte_cdk.sources.concurrent_source.thread_pool_manager import ThreadPoolManager
 from airbyte_cdk.sources.message import InMemoryMessageRepository, MessageRepository
@@ -110,9 +111,14 @@ def read(
         streams: List[AbstractStream],
     ) -> Iterator[AirbyteMessage]:
         self._logger.info("Starting syncing")
+        # Shared across the generator, reader, and processor so that a stream-wide failure on one
+        # partition stops the stream's remaining partitions instead of repeating a doomed request.
+        stream_abort_registry = StreamAbortRegistry()
         concurrent_stream_processor = ConcurrentReadProcessor(
             streams,
-            PartitionEnqueuer(self._queue, self._threadpool),
+            PartitionEnqueuer(
+                self._queue, self._threadpool, stream_abort_registry=stream_abort_registry
+            ),
             self._threadpool,
             self._logger,
             self._slice_logger,
@@ -120,8 +126,10 @@ def read(
             PartitionReader(
                 self._queue,
                 PartitionLogger(self._slice_logger, self._logger, self._message_repository),
+                stream_abort_registry=stream_abort_registry,
             ),
             max_concurrent_partition_generators=self._initial_number_partitions_to_generate,
+            stream_abort_registry=stream_abort_registry,
         )
 
         # Enqueue initial partition generation tasks
diff --git a/airbyte_cdk/sources/concurrent_source/stream_abort_registry.py b/airbyte_cdk/sources/concurrent_source/stream_abort_registry.py
new file mode 100644
index 000000000..ab38e8e0b
--- /dev/null
+++ b/airbyte_cdk/sources/concurrent_source/stream_abort_registry.py
@@ -0,0 +1,31 @@
+# Copyright (c) 2026 Airbyte, Inc., all rights reserved.
+
+import threading
+from typing import Set
+
+
+class StreamAbortRegistry:
+    """Thread-safe registry of streams whose remaining partitions should be skipped.
+
+    When a partition raises a fatal, stream-wide error (e.g. an authorization failure
+    that affects every partition of the stream), the concurrent reader records the
+    stream here. Partitions that are still queued or not yet started then short-circuit
+    instead of repeating the same doomed request, so the stream fails fast rather than
+    exhausting every remaining partition.
+
+    The registry is shared between the main thread (which marks streams as aborted) and
+    the worker threads generating and reading partitions (which check it), so all access
+    is guarded by a lock.
+    """
+
+    def __init__(self) -> None:
+        self._aborted: Set[str] = set()
+        self._lock = threading.Lock()
+
+    def abort(self, stream_name: str) -> None:
+        with self._lock:
+            self._aborted.add(stream_name)
+
+    def is_aborted(self, stream_name: str) -> bool:
+        with self._lock:
+            return stream_name in self._aborted
diff --git a/airbyte_cdk/sources/declarative/declarative_component_schema.yaml b/airbyte_cdk/sources/declarative/declarative_component_schema.yaml
index b78f09883..4e75c6a25 100644
--- a/airbyte_cdk/sources/declarative/declarative_component_schema.yaml
+++ b/airbyte_cdk/sources/declarative/declarative_component_schema.yaml
@@ -2555,6 +2555,14 @@ definitions:
         type: array
         items:
           "$ref": "#/definitions/TypesMap"
+      default_type:
+        title: Default Type
+        description: The default Airbyte type to use when no type mapping matches the source field type.
+        type: string
+        examples:
+          - "string"
+          - "number"
+          - "integer"
       $parameters:
         type: object
         additionalProperties: true
diff --git a/airbyte_cdk/sources/declarative/models/declarative_component_schema.py b/airbyte_cdk/sources/declarative/models/declarative_component_schema.py
index 4c22d38df..bd3b50bec 100644
--- a/airbyte_cdk/sources/declarative/models/declarative_component_schema.py
+++ b/airbyte_cdk/sources/declarative/models/declarative_component_schema.py
@@ -646,6 +646,11 @@ class SchemaTypeIdentifier(BaseModel):
         title="Type Path",
     )
     types_mapping: Optional[List[TypesMap]] = None
+    default_type: Optional[str] = Field(
+        None,
+        description="The default Airbyte type to use when no type mapping matches the source field type.",
+        title="Default Type",
+    )
     parameters: Optional[Dict[str, Any]] = Field(None, alias="$parameters")
 
 
diff --git a/airbyte_cdk/sources/declarative/parsers/model_to_component_factory.py b/airbyte_cdk/sources/declarative/parsers/model_to_component_factory.py
index 82798e02e..16ebeac21 100644
--- a/airbyte_cdk/sources/declarative/parsers/model_to_component_factory.py
+++ b/airbyte_cdk/sources/declarative/parsers/model_to_component_factory.py
@@ -2600,6 +2600,7 @@ def create_schema_type_identifier(
             key_pointer=model_key_pointer,
             type_pointer=model_type_pointer,
             types_mapping=types_mapping,
+            default_type=model.default_type,
             parameters=model.parameters or {},
         )
 
diff --git a/airbyte_cdk/sources/declarative/schema/dynamic_schema_loader.py b/airbyte_cdk/sources/declarative/schema/dynamic_schema_loader.py
index 7d5946a12..fa46f5648 100644
--- a/airbyte_cdk/sources/declarative/schema/dynamic_schema_loader.py
+++ b/airbyte_cdk/sources/declarative/schema/dynamic_schema_loader.py
@@ -89,6 +89,7 @@ class SchemaTypeIdentifier:
     type_pointer: Optional[List[Union[InterpolatedString, str]]] = None
     types_mapping: Optional[List[TypesMap]] = None
     schema_pointer: Optional[List[Union[InterpolatedString, str]]] = None
+    default_type: Optional[str] = None
 
     def __post_init__(self, parameters: Mapping[str, Any]) -> None:
         self.schema_pointer = (
@@ -215,6 +216,7 @@ def _get_type(
             else "string"
         )
         mapped_field_type = self._replace_type_if_not_valid(raw_field_type, raw_schema)
+        type_was_mapped = mapped_field_type is not raw_field_type
         if (
             isinstance(mapped_field_type, list)
             and len(mapped_field_type) == 2
@@ -225,7 +227,9 @@ def _get_type(
             return {"oneOf": [first_type, second_type]}
 
         elif isinstance(mapped_field_type, str):
-            return self._get_airbyte_type(mapped_field_type)
+            return self._get_airbyte_type(
+                mapped_field_type, allow_default_fallback=not type_was_mapped
+            )
 
         elif isinstance(mapped_field_type, ComplexFieldType):
             return self._resolve_complex_type(mapped_field_type)
@@ -269,12 +273,19 @@ def _replace_type_if_not_valid(
                     return types_map.target_type
         return field_type
 
-    @staticmethod
-    def _get_airbyte_type(field_type: str) -> MutableMapping[str, Any]:
+    def _get_airbyte_type(
+        self, field_type: str, *, allow_default_fallback: bool = False
+    ) -> MutableMapping[str, Any]:
         """
         Maps a field type to its corresponding Airbyte type definition.
+        Falls back to `default_type` when `allow_default_fallback` is True and `field_type` is not recognized.
         """
         if field_type not in AIRBYTE_DATA_TYPES:
+            default_type = self.schema_type_identifier.default_type
+            if allow_default_fallback and default_type is not None:
+                if default_type not in AIRBYTE_DATA_TYPES:
+                    raise ValueError(f"Invalid default Airbyte data type: {default_type}")
+                return deepcopy(AIRBYTE_DATA_TYPES[default_type])
             raise ValueError(f"Invalid Airbyte data type: {field_type}")
 
         return deepcopy(AIRBYTE_DATA_TYPES[field_type])
diff --git a/airbyte_cdk/sources/streams/concurrent/partition_enqueuer.py b/airbyte_cdk/sources/streams/concurrent/partition_enqueuer.py
index a4dd81f29..0541daa02 100644
--- a/airbyte_cdk/sources/streams/concurrent/partition_enqueuer.py
+++ b/airbyte_cdk/sources/streams/concurrent/partition_enqueuer.py
@@ -3,10 +3,12 @@
 #
 import time
 from queue import Queue
+from typing import Optional
 
 from airbyte_cdk.sources.concurrent_source.partition_generation_completed_sentinel import (
     PartitionGenerationCompletedSentinel,
 )
+from airbyte_cdk.sources.concurrent_source.stream_abort_registry import StreamAbortRegistry
 from airbyte_cdk.sources.concurrent_source.stream_thread_exception import StreamThreadException
 from airbyte_cdk.sources.concurrent_source.thread_pool_manager import ThreadPoolManager
 from airbyte_cdk.sources.streams.concurrent.abstract_stream import AbstractStream
@@ -23,14 +25,18 @@ def __init__(
         queue: Queue[QueueItem],
         thread_pool_manager: ThreadPoolManager,
         sleep_time_in_seconds: float = 0.1,
+        stream_abort_registry: Optional[StreamAbortRegistry] = None,
     ) -> None:
         """
         :param queue:  The queue to put the partitions in.
         :param throttler: The throttler to use to throttle the partition generation.
+        :param stream_abort_registry: Optional registry of streams that failed fatally. Partition
+            generation stops early for a stream once it has been aborted.
         """
         self._queue = queue
         self._thread_pool_manager = thread_pool_manager
         self._sleep_time_in_seconds = sleep_time_in_seconds
+        self._stream_abort_registry = stream_abort_registry
 
     def generate_partitions(self, stream: AbstractStream) -> None:
         """
@@ -44,6 +50,12 @@ def generate_partitions(self, stream: AbstractStream) -> None:
         """
         try:
             for partition in stream.generate_partitions():
+                # If the stream already failed fatally on another partition, stop generating new
+                # ones. Remaining partitions would only repeat the same doomed request.
+                if self._stream_abort_registry and self._stream_abort_registry.is_aborted(
+                    stream.name
+                ):
+                    break
                 # Adding partitions to the queue generates futures. To avoid having too many futures, we throttle here. We understand that
                 # we might add more futures than the limit by throttling in the threads while it is the main thread that actual adds the
                 # future but we expect the delta between the max futures length and the actual to be small enough that it would not be an
diff --git a/airbyte_cdk/sources/streams/concurrent/partition_reader.py b/airbyte_cdk/sources/streams/concurrent/partition_reader.py
index 0edc5056a..5dded6524 100644
--- a/airbyte_cdk/sources/streams/concurrent/partition_reader.py
+++ b/airbyte_cdk/sources/streams/concurrent/partition_reader.py
@@ -4,6 +4,7 @@
 from queue import Queue
 from typing import Optional
 
+from airbyte_cdk.sources.concurrent_source.stream_abort_registry import StreamAbortRegistry
 from airbyte_cdk.sources.concurrent_source.stream_thread_exception import StreamThreadException
 from airbyte_cdk.sources.message.repository import MessageRepository
 from airbyte_cdk.sources.streams.concurrent.cursor import Cursor
@@ -53,12 +54,17 @@ def __init__(
         self,
         queue: Queue[QueueItem],
         partition_logger: Optional[PartitionLogger] = None,
+        stream_abort_registry: Optional[StreamAbortRegistry] = None,
     ) -> None:
         """
         :param queue: The queue to put the records in.
+        :param partition_logger: Optional logger used to emit a slice log message per partition.
+        :param stream_abort_registry: Optional registry of streams that failed fatally. Partitions
+            belonging to an aborted stream are skipped instead of being read.
         """
         self._queue = queue
         self._partition_logger = partition_logger
+        self._stream_abort_registry = stream_abort_registry
 
     def process_partition(self, partition: Partition, cursor: Cursor) -> None:
         """
@@ -72,6 +78,15 @@ def process_partition(self, partition: Partition, cursor: Cursor) -> None:
         :param partition: The partition to read data from
         :return: None
         """
+        # If the stream already failed fatally on another partition, skip this one instead of
+        # repeating the same doomed request. We do not close the partition on the cursor so that
+        # state is not advanced past the failure.
+        if self._stream_abort_registry and self._stream_abort_registry.is_aborted(
+            partition.stream_name()
+        ):
+            self._queue.put(PartitionCompleteSentinel(partition, not self._IS_SUCCESSFUL))
+            return
+
         try:
             if self._partition_logger:
                 self._partition_logger.log(partition)
diff --git a/unit_tests/sources/declarative/schema/test_dynamic_schema_loader.py b/unit_tests/sources/declarative/schema/test_dynamic_schema_loader.py
index 20147465f..c89a39517 100644
--- a/unit_tests/sources/declarative/schema/test_dynamic_schema_loader.py
+++ b/unit_tests/sources/declarative/schema/test_dynamic_schema_loader.py
@@ -13,6 +13,7 @@
     TestLimits,
 )
 from airbyte_cdk.sources.declarative.schema import DynamicSchemaLoader, SchemaTypeIdentifier
+from airbyte_cdk.sources.declarative.schema.dynamic_schema_loader import TypesMap
 from airbyte_cdk.test.mock_http import HttpMocker, HttpRequest, HttpResponse
 
 _CONFIG = {
@@ -309,6 +310,153 @@ def test_dynamic_schema_loader_manifest_flow():
     assert actual_catalog.streams[0].json_schema == expected_schema
 
 
+@pytest.mark.parametrize(
+    "retriever_data, default_type, expected_schema",
+    [
+        pytest.param(
+            iter(
+                [
+                    {
+                        "schema": [
+                            {"key": "name", "type": "string"},
+                            {"key": "custom_field", "type": "unknown_source_type"},
+                        ]
+                    }
+                ]
+            ),
+            "string",
+            {
+                "$schema": "https://json-schema.org/draft-07/schema#",
+                "additionalProperties": True,
+                "type": "object",
+                "properties": {
+                    "name": {"type": ["null", "string"]},
+                    "custom_field": {"type": ["null", "string"]},
+                },
+            },
+            id="unmapped_type_falls_back_to_default",
+        ),
+        pytest.param(
+            iter(
+                [
+                    {
+                        "schema": [
+                            {"key": "count", "type": "integer"},
+                            {"key": "blob", "type": "exotic_plugin_type"},
+                        ]
+                    }
+                ]
+            ),
+            "string",
+            {
+                "$schema": "https://json-schema.org/draft-07/schema#",
+                "additionalProperties": True,
+                "type": "object",
+                "properties": {
+                    "count": {"type": ["null", "integer"]},
+                    "blob": {"type": ["null", "string"]},
+                },
+            },
+            id="valid_type_unchanged_unknown_type_uses_default",
+        ),
+    ],
+)
+def test_dynamic_schema_loader_default_type(retriever_data, default_type, expected_schema):
+    schema_type_identifier = SchemaTypeIdentifier(
+        schema_pointer=["schema"],
+        key_pointer=["key"],
+        type_pointer=["type"],
+        types_mapping=[],
+        default_type=default_type,
+        parameters={},
+    )
+    loader = DynamicSchemaLoader(
+        retriever=MagicMock(),
+        config=MagicMock(),
+        parameters={},
+        schema_type_identifier=schema_type_identifier,
+    )
+    loader.retriever.read_records = MagicMock(return_value=retriever_data)
+
+    schema = loader.get_json_schema()
+    assert schema == expected_schema
+
+
+def test_dynamic_schema_loader_no_default_type_raises_on_unknown():
+    schema_type_identifier = SchemaTypeIdentifier(
+        schema_pointer=["schema"],
+        key_pointer=["key"],
+        type_pointer=["type"],
+        types_mapping=[],
+        parameters={},
+    )
+    loader = DynamicSchemaLoader(
+        retriever=MagicMock(),
+        config=MagicMock(),
+        parameters={},
+        schema_type_identifier=schema_type_identifier,
+    )
+    loader.retriever.read_records = MagicMock(
+        return_value=iter([{"schema": [{"key": "field", "type": "totally_unknown"}]}])
+    )
+
+    with pytest.raises(ValueError, match="Invalid Airbyte data type: totally_unknown"):
+        loader.get_json_schema()
+
+
+def test_dynamic_schema_loader_invalid_default_type_raises():
+    schema_type_identifier = SchemaTypeIdentifier(
+        schema_pointer=["schema"],
+        key_pointer=["key"],
+        type_pointer=["type"],
+        types_mapping=[],
+        default_type="not_a_real_airbyte_type",
+        parameters={},
+    )
+    loader = DynamicSchemaLoader(
+        retriever=MagicMock(),
+        config=MagicMock(),
+        parameters={},
+        schema_type_identifier=schema_type_identifier,
+    )
+    loader.retriever.read_records = MagicMock(
+        return_value=iter([{"schema": [{"key": "field", "type": "unknown"}]}])
+    )
+
+    with pytest.raises(
+        ValueError,
+        match="Invalid default Airbyte data type: not_a_real_airbyte_type",
+    ):
+        loader.get_json_schema()
+
+
+def test_dynamic_schema_loader_bad_mapping_target_not_masked_by_default_type():
+    schema_type_identifier = SchemaTypeIdentifier(
+        schema_pointer=["schema"],
+        key_pointer=["key"],
+        type_pointer=["type"],
+        types_mapping=[
+            TypesMap(
+                target_type="not_a_real_airbyte_type", current_type="bad_source", condition=None
+            ),
+        ],
+        default_type="string",
+        parameters={},
+    )
+    loader = DynamicSchemaLoader(
+        retriever=MagicMock(),
+        config=MagicMock(),
+        parameters={},
+        schema_type_identifier=schema_type_identifier,
+    )
+    loader.retriever.read_records = MagicMock(
+        return_value=iter([{"schema": [{"key": "field", "type": "bad_source"}]}])
+    )
+
+    with pytest.raises(ValueError, match="Invalid Airbyte data type: not_a_real_airbyte_type"):
+        loader.get_json_schema()
+
+
 def test_dynamic_schema_loader_with_type_conditions():
     _MANIFEST_WITH_TYPE_CONDITIONS = deepcopy(_MANIFEST)
     _MANIFEST_WITH_TYPE_CONDITIONS["definitions"]["party_members_stream"]["schema_loader"][