diff --git a/datadog_sync/utils/resource_utils.py b/datadog_sync/utils/resource_utils.py
index 7fe29c71..800d2dbb 100644
--- a/datadog_sync/utils/resource_utils.py
+++ b/datadog_sync/utils/resource_utils.py
@@ -4,12 +4,14 @@
 # Copyright 2019 Datadog, Inc.
 
 from __future__ import annotations
+import asyncio
 import re
 import logging
 from copy import deepcopy
 from graphlib import TopologicalSorter, CycleError
 from dateutil.parser import parse
 
+import aiohttp
 from deepdiff import DeepDiff
 from deepdiff.operator import BaseOperator
 
@@ -26,6 +28,30 @@
 DEFAULT_TAGS = ["managed_by:datadog-sync"]
 
 
+# aiohttp timeout family — both have empty ``str()``.
+_TIMEOUT_EXC_TYPES = (asyncio.TimeoutError, aiohttp.ServerTimeoutError)
+
+
+def format_exc_for_log(exc: BaseException) -> str:
+    """Render an exception for ERROR-level logging without producing an empty body.
+
+    Bare ``str(exc)`` is empty for ``aiohttp.ServerTimeoutError()`` /
+    ``asyncio.TimeoutError()`` / ``aiohttp.ClientOSError()`` with no args,
+    producing log lines ending in ``-`` with no diagnostic.
+
+    Rules: timeout family → ``timeout: <ClassName>[: <msg>]`` (greppable token);
+    non-empty ``str(exc)`` → verbatim; empty ``str(exc)`` → class name fallback.
+    """
+    if isinstance(exc, _TIMEOUT_EXC_TYPES):
+        msg = str(exc)
+        cls = type(exc).__name__
+        return f"timeout: {cls}: {msg}" if msg else f"timeout: {cls}"
+    msg = str(exc)
+    if msg:
+        return msg
+    return type(exc).__name__
+
+
 class SkipResource(Exception):
     def __init__(self, _id: str, _type: str, msg: str):
         super(SkipResource, self).__init__(f"Skipping {_type} with id: {_id}. {msg}")
diff --git a/datadog_sync/utils/resources_handler.py b/datadog_sync/utils/resources_handler.py
index 3c2044b8..9bcd68fd 100644
--- a/datadog_sync/utils/resources_handler.py
+++ b/datadog_sync/utils/resources_handler.py
@@ -25,6 +25,7 @@
     check_diff,
     create_global_downtime,
     find_attr,
+    format_exc_for_log,
     prep_resource,
     init_topological_sorter,
 )
@@ -350,7 +351,8 @@ async def _apply_resource_cb(self, q_item: List) -> None:
         except Exception as e:
             self.worker.counter.increment_failure()
             self._emit(resource_type, _id, "sync", "failure", reason=self._sanitize_reason(e))
-            self.config.logger.error(str(e), resource_type=resource_type, _id=_id)
+            # format_exc_for_log guards against empty-str() exceptions producing blank log bodies.
+            self.config.logger.error(format_exc_for_log(e), resource_type=resource_type, _id=_id)
             await r_class._send_action_metrics(Command.SYNC.value, _id, Status.FAILURE.value)
         finally:
             # always place in done queue regardless of exception thrown
@@ -639,8 +641,12 @@ async def _import_resource(self, q_item: List) -> None:
             self.worker.counter.increment_failure()
             self._emit(resource_type, _id, "import", "failure", reason=self._sanitize_reason(e))
             await r_class._send_action_metrics(Command.IMPORT.value, _id, Status.FAILURE.value)
-            self.config.logger.error(f"error while importing resource: resource_type:{resource_type} id:{_id}")
-            self.config.logger.debug(f"error detail: {str(e)}", resource_type=resource_type)
+            # Attach exception detail at ERROR level (previously DEBUG-only, invisible at default verbosity).
+            self.config.logger.error(
+                f"error while importing resource: {format_exc_for_log(e)}",
+                resource_type=resource_type,
+                _id=_id,
+            )
 
     async def prune(self) -> None:
         """Delete per-resource state files for source IDs no longer present.
@@ -750,11 +756,19 @@ async def _force_missing_dep_import_cb(self, q_item: List):
             return
         except CustomClientHTTPError as e:
             self._emit(resource_type, _id, "import", "failure", reason=self._sanitize_reason(e))
-            self.config.logger.error(f"error importing dependency: {str(e)}", resource_type=resource_type, _id=_id)
+            self.config.logger.error(
+                f"error importing dependency: {format_exc_for_log(e)}",
+                resource_type=resource_type,
+                _id=_id,
+            )
             return
         except Exception as e:
             self._emit(resource_type, _id, "import", "failure", reason=self._sanitize_reason(e))
-            self.config.logger.error(f"error importing dependency: {str(e)}", resource_type=resource_type, _id=_id)
+            self.config.logger.error(
+                f"error importing dependency: {format_exc_for_log(e)}",
+                resource_type=resource_type,
+                _id=_id,
+            )
             return
 
         failed_connections, missing_deps = self._resource_connections(resource_type, _id)
@@ -785,7 +799,7 @@ async def _cleanup_worker(self, q_item: List) -> None:
             self.worker.counter.increment_failure()
             self._emit(resource_type, _id, "delete", "failure", reason=self._sanitize_reason(e))
             await r_class._send_action_metrics("delete", _id, Status.FAILURE.value)
-            self.config.logger.error(f"error deleting resource {resource_type} with id {_id}: {str(e)}")
+            self.config.logger.error(f"error deleting resource {resource_type} with id {_id}: {format_exc_for_log(e)}")
         finally:
             # Mark as done in cleanup sorter if it exists
             if hasattr(self, "cleanup_sorter") and self.cleanup_sorter:
diff --git a/tests/unit/test_notebooks_error_formatting.py b/tests/unit/test_notebooks_error_formatting.py
new file mode 100644
index 00000000..06362a4c
--- /dev/null
+++ b/tests/unit/test_notebooks_error_formatting.py
@@ -0,0 +1,190 @@
+# Unless explicitly stated otherwise all files in this repository are licensed
+# under the 3-clause BSD style license (see LICENSE).
+# This product includes software developed at Datadog (https://www.datadoghq.com/).
+# Copyright 2019 Datadog, Inc.
+
+"""Tests for ``format_exc_for_log`` and the sync/import error-log call sites.
+
+Pins the contract that empty-``str()`` exceptions (e.g.
+``aiohttp.ServerTimeoutError()``) never produce blank ERROR log bodies.
+"""
+
+import asyncio
+from unittest.mock import AsyncMock, MagicMock
+
+import aiohttp
+
+from datadog_sync.utils.resource_utils import (
+    CustomClientHTTPError,
+    format_exc_for_log,
+)
+from datadog_sync.utils.resources_handler import ResourcesHandler
+
+# --- format_exc_for_log unit tests ---------------------------------------
+
+
+def test_format_exc_for_log_preserves_non_empty_message():
+    """Common case: non-empty exception message passes through verbatim."""
+    e = ValueError("bad input")
+    assert format_exc_for_log(e) == "bad input"
+
+
+def test_format_exc_for_log_preserves_http_error_message():
+    """CustomClientHTTPError must pass through unchanged."""
+    from types import SimpleNamespace
+
+    err = CustomClientHTTPError(
+        SimpleNamespace(status=500, message="Internal Server Error"),
+        message="upstream returned 500",
+    )
+    out = format_exc_for_log(err)
+    assert "500" in out, f"expected status code in formatted output, got {out!r}"
+    assert "upstream returned 500" in out, f"expected body in formatted output, got {out!r}"
+
+
+def test_format_exc_for_log_empty_string_falls_back_to_type_name():
+    """Empty-str() exception must surface its class name."""
+
+    class _MyError(Exception):
+        pass
+
+    e = _MyError()
+    assert str(e) == "", "precondition: bare exception has empty str()"
+    out = format_exc_for_log(e)
+    assert "_MyError" in out, f"empty-message exception must surface its type name; got {out!r}"
+
+
+def test_format_exc_for_log_aiohttp_server_timeout_emits_timeout_marker():
+    """ServerTimeoutError must produce a greppable 'timeout:' marker + class name."""
+    e = aiohttp.ServerTimeoutError()
+    assert str(e) == "", "precondition: bare ServerTimeoutError has empty str()"
+    out = format_exc_for_log(e)
+    assert "timeout" in out.lower(), f"expected 'timeout' marker; got {out!r}"
+    assert "ServerTimeoutError" in out, f"expected class name; got {out!r}"
+
+
+def test_format_exc_for_log_asyncio_timeout_emits_timeout_marker():
+    """asyncio.TimeoutError must produce the same 'timeout:' marker as ServerTimeoutError."""
+    e = asyncio.TimeoutError()
+    assert str(e) == "", "precondition: bare asyncio.TimeoutError has empty str()"
+    out = format_exc_for_log(e)
+    assert "timeout" in out.lower(), f"expected 'timeout' marker; got {out!r}"
+
+
+def test_format_exc_for_log_client_os_error_falls_back_to_type():
+    """ClientOSError (empty-str, non-timeout) must surface its class name."""
+    e = aiohttp.ClientOSError()
+    assert str(e) == "", "precondition: bare ClientOSError has empty str()"
+    out = format_exc_for_log(e)
+    assert "ClientOSError" in out, f"expected class name; got {out!r}"
+
+
+# --- ResourcesHandler integration tests ----------------------------------
+
+
+def _drive_apply_cb(mock_config, resource_type, _id, exc):
+    """Drive ``_apply_resource_cb`` so ``connect_resources`` raises ``exc``."""
+    r_class = MagicMock()
+    r_class.resource_config = MagicMock(concurrent=True)
+    r_class.connect_resources = MagicMock(side_effect=exc)
+    r_class._pre_resource_action_hook = AsyncMock()
+    r_class._send_action_metrics = AsyncMock()
+
+    mock_config.resources = {resource_type: r_class}
+    mock_config.state.source[resource_type][_id] = {"id": _id}
+
+    handler = ResourcesHandler(mock_config)
+    handler.worker = MagicMock()
+    handler.worker.counter = MagicMock()
+    handler.sorter = MagicMock()
+    handler._emit = MagicMock()
+
+    asyncio.run(handler._apply_resource_cb([resource_type, _id]))
+    return handler
+
+
+def _drive_import_resource(mock_config, resource_type, _id, exc):
+    """Drive ``_import_resource`` so ``r_class._import_resource`` raises ``exc``."""
+    r_class = MagicMock()
+    r_class.resource_config = MagicMock(
+        list_omitted_attr_prefixes=[],
+        excluded_attributes=[],
+    )
+    r_class._import_resource = AsyncMock(side_effect=exc)
+    r_class._send_action_metrics = AsyncMock()
+    r_class.filter = MagicMock(return_value=True)
+
+    mock_config.resources = {resource_type: r_class}
+    mock_config.filters = []
+
+    handler = ResourcesHandler(mock_config)
+    handler.worker = MagicMock()
+    handler.worker.counter = MagicMock()
+    handler._emit = MagicMock()
+
+    asyncio.run(handler._import_resource([resource_type, {"id": _id}]))
+    return handler
+
+
+def test_apply_cb_empty_timeout_surfaces_marker(mock_config):
+    """ServerTimeoutError on the apply path must emit a 'timeout:' marker, not a blank body."""
+    exc = aiohttp.ServerTimeoutError()
+    _drive_apply_cb(mock_config, "notebooks", "n-1", exc)
+
+    mock_config.logger.error.assert_called_once()
+    args, kwargs = mock_config.logger.error.call_args
+    assert args[0], f"logger.error must not be called with empty message; got args={args!r}"
+    assert "timeout" in args[0].lower(), f"timeout exception must produce a 'timeout' marker; got {args[0]!r}"
+    assert kwargs == {"resource_type": "notebooks", "_id": "n-1"}
+
+
+def test_apply_cb_empty_exception_surfaces_type_name(mock_config):
+    """ClientOSError on the apply path must surface its class name, not a blank body."""
+    exc = aiohttp.ClientOSError()
+    _drive_apply_cb(mock_config, "notebooks", "n-2", exc)
+
+    mock_config.logger.error.assert_called_once()
+    args, _ = mock_config.logger.error.call_args
+    assert args[0], f"logger.error must not be called with empty message; got args={args!r}"
+    assert "ClientOSError" in args[0], f"empty-message exception must surface its type name; got {args[0]!r}"
+
+
+def test_apply_cb_normal_exception_message_preserved(mock_config):
+    """Regression guard: non-empty exception messages must pass through unchanged."""
+    exc = ValueError("bad notebook payload: cells[0].definition missing")
+    _drive_apply_cb(mock_config, "notebooks", "n-3", exc)
+
+    mock_config.logger.error.assert_called_once()
+    args, _ = mock_config.logger.error.call_args
+    assert (
+        args[0] == "bad notebook payload: cells[0].definition missing"
+    ), f"non-empty exception message must be preserved verbatim; got {args[0]!r}"
+
+
+def test_apply_cb_http_error_message_preserved(mock_config):
+    """CustomClientHTTPError must carry status + body through to the ERROR line."""
+    from types import SimpleNamespace
+
+    exc = CustomClientHTTPError(
+        SimpleNamespace(status=503, message="Service Unavailable"),
+        message="upstream is down",
+    )
+    _drive_apply_cb(mock_config, "notebooks", "n-4", exc)
+
+    mock_config.logger.error.assert_called_once()
+    args, _ = mock_config.logger.error.call_args
+    assert "503" in args[0], f"HTTP status must be preserved in error log; got {args[0]!r}"
+    assert "upstream is down" in args[0], f"HTTP body must be preserved; got {args[0]!r}"
+
+
+def test_import_path_empty_timeout_surfaces_marker_at_error_level(mock_config):
+    """Import path must surface the 'timeout:' marker at ERROR level (not DEBUG-only)."""
+    exc = aiohttp.ServerTimeoutError()
+    _drive_import_resource(mock_config, "notebooks", "n-5", exc)
+
+    error_calls = list(mock_config.logger.error.call_args_list)
+    formatted_msgs = [c.args[0] for c in error_calls if c.args]
+    timeout_marked = [m for m in formatted_msgs if "timeout" in m.lower()]
+    assert (
+        timeout_marked
+    ), f"import path must surface 'timeout' marker at ERROR level; got error msgs={formatted_msgs!r}"