Hey @Asad Hazara 

The 400 Bad Request error you're experiencing is unusual, especially since you're not dealing with SMS-related data.

Can you make sure a few things and see if that fixes your issue?

-Ensure you're using either email OR external_id consistently. Don't mix identification methods within the same batch

-Verify your API headers are correct. Double-check the API revision date and ensure your API key has sufficient permissions

-for API request optimisation - Keep batches under 1000 events. Add delays between bulk requests

If this still doesn’t work, can you try contacting Klaviyo support here?

I hope this helps and thank you for posting your question here in the community.

Cheers

Arpit

Hi Arpit, first of all, thank you for your response.

In my case, this error is thrown even when I only use a correct `_kx` parameter without including an email or `external_id`, so it doesn’t seem related to those profile attributes. This happens occasionally, so it’s likely an issue on Klaviyo’s side. It seems that another issue is triggering this specific error instead of the actual cause. Just to clarify, thousands of batches are sent in the same way and are accepted, so it can’t be the headers, as they are identical for all requests. Also, some failing batches contain only a single event. None of the failing batches are near 1,000 events.

Unfortunately, I can’t contact Klaviyo directly since I’m not a Klaviyo subscriber. We provide software to over 15,000 stores, which use it primarily for ad platforms, and we recently launched Klaviyo. I’ve opened this thread hoping someone at Klaviyo can look into this matter.

Hey @kaila.lawrence @stephen.trumble @chloe.strange - can you please help them with their query?

thanks

​@Asad Hazara, 

We’ll be following up individually on your unique situation. 

~Chloe