LangfuseBatchUploadError
langfuse.client.errors.LangfuseBatchUploadError
Stack trace
langfuse.client.errors.LangfuseBatchUploadError: Batch upload failed with status 400: {"error":"Invalid event format in batch"}
File "/app/langfuse_client.py", line 45, in upload_batch
client.upload_events_batch(events) # triggers error
File "/usr/local/lib/python3.9/site-packages/langfuse/client.py", line 120, in upload_events_batch
raise LangfuseBatchUploadError(f"Batch upload failed with status {response.status_code}: {response.text}") Why it happens
Langfuse expects batch uploads to conform to a strict JSON schema for events. If any event in the batch is malformed, missing required fields, or contains invalid data types, the API rejects the entire batch. Network interruptions or incorrect API keys can also cause upload failures.
Detection
Monitor the client upload method for LangfuseBatchUploadError exceptions and log the full batch payload and API response to identify malformed events before retrying.
Causes & fixes
One or more events in the batch have missing required fields or invalid data types.
Validate each event against Langfuse's event schema before batch upload, ensuring all required fields are present and correctly typed.
API key is missing, invalid, or lacks permissions for batch uploads.
Set the LANGFUSE_API_KEY environment variable correctly and verify the key has batch upload permissions in the Langfuse dashboard.
Network connectivity issues causing incomplete or failed HTTP requests.
Implement retry logic with exponential backoff for batch uploads and verify network stability.
Batch size exceeds Langfuse API limits causing rejection.
Split large event batches into smaller chunks within the documented size limits before uploading.
Code: broken vs fixed
from langfuse import LangfuseClient
client = LangfuseClient()
events = [{"event": "start", "timestamp": "not-a-timestamp"}]
client.upload_events_batch(events) # triggers LangfuseBatchUploadError due to invalid timestampimport os
from langfuse import LangfuseClient
os.environ["LANGFUSE_API_KEY"] = "your_api_key_here" # Set your API key securely
client = LangfuseClient(api_key=os.environ["LANGFUSE_API_KEY"])
# Validate event data before upload
valid_events = [{"event": "start", "timestamp": 1680000000}]
client.upload_events_batch(valid_events) # fixed: valid timestamp and API key
print("Batch upload succeeded")Workaround
Catch LangfuseBatchUploadError, log the full batch payload and error response, then manually inspect and fix malformed events or retry after network issues.
Prevention
Implement strict event validation before batch upload and use automated monitoring to detect and alert on batch upload failures early, ensuring API keys and network stability.