mem0ai/mem0 · error · ValueError

Filter value for {key!r} contains prohibited characters (dou

Error message

Filter value for {key!r} contains prohibited characters (double quote or backslash): {value!r}

What it means

Raised by `_validate_filter` when a string filter value contains a double quote or a backslash. The Upstash filter is built by string interpolation, so these characters could terminate or alter the quoted literal — rejecting them is the injection defense. Values are otherwise passed through verbatim, so escaping is deliberately not attempted.

Source

Thrown at mem0/vector_stores/upstash_vector.py:29

except ImportError:
    raise ImportError("The 'upstash_vector' library is required. Please install it using 'pip install upstash_vector'.")


logger = logging.getLogger(__name__)

_SAFE_FILTER_KEY = re.compile(r"[a-zA-Z_][a-zA-Z0-9_]*\Z")


def _validate_filter(key: str, value: Any) -> None:
    if not isinstance(key, str) or not _SAFE_FILTER_KEY.fullmatch(key):
        raise ValueError(f"Invalid filter key: {key!r}")
    if not isinstance(value, (str, int, float, bool)):
        raise ValueError(
            f"Filter value for {key!r} must be str, int, float, or bool, "
            f"got {type(value).__name__}"
        )
    if isinstance(value, str) and ('"' in value or "\\" in value):
        raise ValueError(
            f"Filter value for {key!r} contains prohibited characters "
            f"(double quote or backslash): {value!r}"
        )


class OutputData(BaseModel):
    id: Optional[str]  # memory id
    score: Optional[float]  # is None for `get` method
    payload: Optional[Dict]  # metadata


class UpstashVector(VectorStoreBase):
    def __init__(
        self,
        collection_name: str,
        url: Optional[str] = None,
        token: Optional[str] = None,
        client: Optional[Index] = None,

View on GitHub (pinned to 001c235229)

Solutions

1. Sanitize at the boundary: strip or reject `"` and `\\` in any value destined for an Upstash filter.
2. Better, filter on stable identifiers (IDs, slugs, hashes) instead of free-form text — store the text in the payload, match on the identifier.
3. If the character matters, encode it (e.g. percent-encoding or a hash of the value) consistently at write and read time.

Example fix

# before
name = 'assistant "pro"'
memory.search("q", filters={"agent_name": name})  # ValueError

# after
import hashlib
slug = "assistant-pro"  # or hashlib.sha256(name.encode()).hexdigest()
memory.add("...", metadata={"agent_name": name, "agent_slug": slug})
memory.search("q", filters={"agent_slug": slug})

def safe_filter_value(value: str) -> str:
    if '\"' in value or "\\" in value:
        raise ValueError("Filter value contains double quote or backslash; filter on an identifier instead")
    return value

def is_safe_filter_string(v) -> bool:
    return isinstance(v, str) and '\"' not in v and "\\" not in v

try:
    results = memory.search("q", filters=filters)
except ValueError as e:
    if "prohibited characters" in str(e):
        raise BadRequest("Filter values must not contain quotes or backslashes") from e
    raise

When it happens

Trigger: Filtering on values containing `"` (e.g. agent names like `assistant "pro"`), Windows-style paths with backslashes (`C:\Users\...`), or crafted input such as `u1" OR 1=1 --` attempting filter injection.

Common situations: User-supplied free text (chat titles, agent names, tags) used directly as an equality filter value; LLM-generated filter values quoting terms; passing regexes or file paths as metadata filters.

Related errors

• Invalid filter key: {key!r}
• Filter value for {key!r} must be str, int, float, or bool, g
• AND filter value must be a list of filter dicts, got ${typeo
• OR filter value must be a list of filter dicts, got ${typeof
• NOT filter value must be a list of filter dicts, got ${typeo

AI-assisted analysis of mem0ai/mem0@001c235229 (2026-08-15). Data as JSON: /api/errors/dc0b7c87732de0d8. Report an issue: GitHub.