diff --git a/haystack/utils/filters.py b/haystack/utils/filters.py
index 5d89e9eefab..6fb9afcc129 100644
--- a/haystack/utils/filters.py
+++ b/haystack/utils/filters.py
@@ -48,6 +48,10 @@ def _not(document: Document | ByteStream, conditions: list[dict[str, Any]]) -> b
 LOGICAL_OPERATORS = {"NOT": _not, "OR": _or, "AND": _and}
 
 
+def _valid_operators_message(operators: dict[str, Any]) -> str:
+    return ", ".join(f"'{operator}'" for operator in sorted(operators))
+
+
 def _equal(value: Any, filter_value: Any) -> bool:
     return value == filter_value
 
@@ -173,6 +177,12 @@ def _logic_condition(condition: dict[str, Any], document: Document | ByteStream)
         msg = f"'conditions' key missing in {condition}"
         raise FilterError(msg)
     operator: str = condition["operator"]
+    if operator not in LOGICAL_OPERATORS:
+        msg = (
+            f"Unsupported logical operator '{operator}'. "
+            f"Valid operators are: {_valid_operators_message(LOGICAL_OPERATORS)}."
+        )
+        raise FilterError(msg)
     conditions: list[dict[str, Any]] = condition["conditions"]
     return LOGICAL_OPERATORS[operator](document=document, conditions=conditions)
 
@@ -214,5 +224,11 @@ def _comparison_condition(condition: dict[str, Any], document: Document | ByteSt
     else:
         document_value = getattr(document, field)
     operator: str = condition["operator"]
+    if operator not in COMPARISON_OPERATORS:
+        msg = (
+            f"Unsupported comparison operator '{operator}'. "
+            f"Valid operators are: {_valid_operators_message(COMPARISON_OPERATORS)}."
+        )
+        raise FilterError(msg)
     filter_value: Any = condition["value"]
     return COMPARISON_OPERATORS[operator](filter_value=filter_value, value=document_value)
diff --git a/test/utils/test_filters.py b/test/utils/test_filters.py
index f5fbf66d6a8..c717cff5981 100644
--- a/test/utils/test_filters.py
+++ b/test/utils/test_filters.py
@@ -574,3 +574,32 @@ def test_document_matches_filter_raises_error(filters):
     with pytest.raises(FilterError):
         document = Document(meta={"page": 10})
         document_matches_filter(filters, document)
+
+
+@pytest.mark.parametrize(
+    "filters, error_message, expected_valid_operators",
+    [
+        pytest.param(
+            {"field": "meta.page", "operator": "gt", "value": 1},
+            "Unsupported comparison operator 'gt'",
+            ["'=='", "'!='", "'>'", "'>='", "'<'", "'<='", "'in'", "'not in'"],
+            id="unknown comparison operator",
+        ),
+        pytest.param(
+            {"operator": "XOR", "conditions": [{"field": "meta.page", "operator": "==", "value": 1}]},
+            "Unsupported logical operator 'XOR'",
+            ["'AND'", "'OR'", "'NOT'"],
+            id="unknown logical operator",
+        ),
+    ],
+)
+def test_document_matches_filter_raises_helpful_error_for_unknown_operator(
+    filters, error_message, expected_valid_operators
+):
+    with pytest.raises(FilterError) as exc_info:
+        document_matches_filter(filters, Document(meta={"page": 10}))
+
+    message = str(exc_info.value)
+    assert error_message in message
+    for operator in expected_valid_operators:
+        assert operator in message