diff --git a/CHANGES.md b/CHANGES.md
index 36c193fb..3966472a 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -6,6 +6,7 @@
 
 - avoid future deprecation for pydantic.Field and use `json_schema_extra` instead of `openapi_examples`
 - use `orjson` based JSONResponse when available
+- changed from `AssertionError` to `HTTPException` for **bbox** parsing exceptions
 
 ## [5.2.0] - 2025-04-18
 
diff --git a/stac_fastapi/api/tests/test_models.py b/stac_fastapi/api/tests/test_models.py
index 032b6002..2f77712d 100644
--- a/stac_fastapi/api/tests/test_models.py
+++ b/stac_fastapi/api/tests/test_models.py
@@ -43,7 +43,10 @@ def test_create_get_request_model():
     model = request_model(bbox="0,0,0,1,1,1")
     assert model.bbox == (0.0, 0.0, 0.0, 1.0, 1.0, 1.0)
 
-    with pytest.raises(AssertionError):
+    with pytest.raises(HTTPException):
+        request_model(bbox="a,b")
+
+    with pytest.raises(HTTPException):
         request_model(bbox="0,0,0,1,1")
 
     model = request_model(
diff --git a/stac_fastapi/types/stac_fastapi/types/search.py b/stac_fastapi/types/stac_fastapi/types/search.py
index f52f4530..01e62273 100644
--- a/stac_fastapi/types/stac_fastapi/types/search.py
+++ b/stac_fastapi/types/stac_fastapi/types/search.py
@@ -5,7 +5,7 @@
 from typing import Dict, List, Optional, Union
 
 import attr
-from fastapi import Query
+from fastapi import HTTPException, Query
 from pydantic import Field, PositiveInt
 from pydantic.functional_validators import AfterValidator
 from stac_pydantic.api import Search
@@ -34,8 +34,16 @@ def str2list(x: str) -> Optional[List[str]]:
 def str2bbox(x: str) -> Optional[BBox]:
     """Convert string to BBox based on , delimiter."""
     if x:
-        t = tuple(float(v) for v in x.split(","))
-        assert len(t) in [4, 6], f"BBox '{x}' must have 4 or 6 values."
+        try:
+            t = tuple(float(v) for v in x.split(","))
+        except ValueError:
+            raise HTTPException(status_code=400, detail=f"invalid bbox: {x}")
+
+        if len(t) not in (4, 6):
+            raise HTTPException(
+                status_code=400, detail=f"BBox '{x}' must have 4 or 6 values."
+            )
+
         return t
 
     return None