diff --git a/backend/open_webui/models/functions.py b/backend/open_webui/models/functions.py
index 3747d9e09a..573880d521 100644
--- a/backend/open_webui/models/functions.py
+++ b/backend/open_webui/models/functions.py
@@ -42,7 +42,7 @@ class FunctionMeta(BaseModel):
 
 class FunctionModel(BaseModel):
     id: str
-    user_id: str
+    user_id: str | None = None  # may be null for legacy/malformed records
     name: str
     type: str
     content: str
@@ -58,7 +58,7 @@ class FunctionModel(BaseModel):
 # --- form / schema definitions ---
 class FunctionWithValvesModel(BaseModel):
     id: str
-    user_id: str
+    user_id: str | None = None  # may be null for legacy/malformed records
     name: str
     type: str
     content: str
@@ -79,7 +79,7 @@ class FunctionWithValvesModel(BaseModel):
 
 class FunctionResponse(BaseModel):
     id: str
-    user_id: str
+    user_id: str | None = None  # may be null for legacy/malformed records
     type: str
     name: str
     meta: FunctionMeta
diff --git a/backend/open_webui/models/tools.py b/backend/open_webui/models/tools.py
index d4bcf1f631..86568288e0 100644
--- a/backend/open_webui/models/tools.py
+++ b/backend/open_webui/models/tools.py
@@ -41,7 +41,7 @@ class ToolMeta(BaseModel):
 
 class ToolModel(BaseModel):
     id: str
-    user_id: str
+    user_id: str | None = None  # may be null for legacy/malformed records
     name: str
     # None when listed with defer_content=True (source skipped for listings)
     content: str | None = None
@@ -66,7 +66,7 @@ class ToolUserModel(ToolModel):
 
 class ToolResponse(BaseModel):
     id: str
-    user_id: str
+    user_id: str | None = None  # may be null for legacy/malformed records
     name: str
     meta: ToolMeta
     access_grants: list[AccessGrantModel] = Field(default_factory=list)