langflow-ai/langflow · warning · HTTPException

Cannot request logs before and after the timestamp

Error message

Cannot request logs before and after the timestamp

What it means

HTTP 400 from GET /api/v1/logs when both lines_before and lines_after query parameters are > 0. The API only supports paging in one direction from a timestamp at a time; asking for both sides of the timestamp in one request is rejected.

Source

Thrown at src/backend/base/langflow/api/log_router.py:92

@log_router.get("/logs", dependencies=[Depends(get_current_active_superuser)])
async def logs(
    lines_before: Annotated[int, Query(description="The number of logs before the timestamp or the last log")] = 0,
    lines_after: Annotated[int, Query(description="The number of logs after the timestamp")] = 0,
    timestamp: Annotated[int, Query(description="The timestamp to start getting logs from")] = 0,
):
    """Retrieve application logs with superuser authentication required.

    SECURITY: Logs may contain sensitive information and require superuser authentication.
    """
    global log_buffer  # noqa: PLW0602
    if log_buffer.enabled() is False:
        raise HTTPException(
            status_code=HTTPStatus.NOT_IMPLEMENTED,
            detail="Log retrieval is disabled",
        )
    if lines_after > 0 and lines_before > 0:
        raise HTTPException(
            status_code=HTTPStatus.BAD_REQUEST,
            detail="Cannot request logs before and after the timestamp",
        )
    if timestamp <= 0:
        if lines_after > 0:
            raise HTTPException(
                status_code=HTTPStatus.BAD_REQUEST,
                detail="Timestamp is required when requesting logs after the timestamp",
            )
        content = log_buffer.get_last_n(10) if lines_before <= 0 else log_buffer.get_last_n(lines_before)
    elif lines_before > 0:
        content = log_buffer.get_before_timestamp(timestamp=timestamp, lines=lines_before)
    elif lines_after > 0:
        content = log_buffer.get_after_timestamp(timestamp=timestamp, lines=lines_after)
    else:
        content = log_buffer.get_before_timestamp(timestamp=timestamp, lines=10)
    return JSONResponse(content=content)

View on GitHub (pinned to 976ec789d2)

Solutions

1. Split into two requests: one with lines_before, one with lines_after
2. Fetch before and after pages separately and merge client-side
3. If you need a continuous window, request get_last_n semantics by omitting timestamp with lines_before only

Example fix

# before
GET /api/v1/logs?timestamp=1700000000&lines_before=10&lines_after=10  # 400
# after
GET /api/v1/logs?timestamp=1700000000&lines_before=10
GET /api/v1/logs?timestamp=1700000000&lines_after=10

const url = new URL('/api/v1/logs', base);
if (linesBefore > 0) url.searchParams.set('lines_before', linesBefore);
if (linesAfter > 0 && !linesBefore) { url.searchParams.set('lines_after', linesAfter); url.searchParams.set('timestamp', ts); }

try { ... } catch (e) { if (e.response?.status === 400 && /before and after/.test(e.detail)) { return merge(await getBefore(ts), await getAfter(ts)); } throw e; }

When it happens

Trigger: Calling /api/v1/logs?lines_before=10&lines_after=10 (optionally with timestamp) as superuser with the log buffer enabled.

Common situations: UI log viewers trying to fetch a context window around a timestamp in a single request; ported client code assuming a 'range' query API.

Related errors

• Timestamp is required when requesting logs after the timesta
• Failed to install MCP
• No supported files found in folder. Allowed types: ${types?.
• File type ${fileExtension} not allowed. Allowed types: ${typ
• Invalid path

AI-assisted analysis of langflow-ai/langflow@976ec789d2 (2026-08-14). Data as JSON: /api/errors/246b675b2f7ea6ef. Report an issue: GitHub.