Troubleshoot an invalid webhook URL

Forum|Forum|6 months ago
February 5, 2026
3 replies
104 views

Hi, I am learning how to build and use webhooks, and trying to create one that adds a profile to a list when they book a specific tour. The webhook URL I am using is: https://a.klaviyo.com/api/lists/{ID}/relationships/profiles that I’ve found from: https://developers.klaviyo.com/en/reference/add_profiles_to_list (changing the {ID} to my list ID, but I keep getting an error that the URL is invalid. Does anyone know where I’m going wrong here?

Thanks so much!

API

Best answer by Byrne C

Hi all.

I can confirm that the error message that you were seeing was unexpected behavior, and our team has worked to fix it. As of now, the incident has been resolved, and webhooks should be able to be created successfully, and fire without errors. Let me know if I can address any additional concerns.

whereisjad

Expert Problem Solver IV

@NatalieRuff are you using the webhook action inside a flow? can you share a screenshot of what the setup looks like. That is assuming that the URL setting uses the hardcoded list ID and not a variable

— Jad A | Klaviyo + Shopify + API Integrations Specialist • 7+ Years' Experience Helping with new setups, seamless integrations, and API connections—happy to connect. http://ja-technical-consulting.xyz/

tsalamazing

Problem Solver I

I'm getting the same invalid URL error since yesterday to event webhooks that were in place for months and working properly.

Since ~20 hours ago, they started failing because of invalid URL. But when I try the same webhook in Postman, it works. It might be a Klaviyo problem. Check if this works in Postman for you or not

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Byrne CAnswer

Community Manager

Hi all.

I can confirm that the error message that you were seeing was unexpected behavior, and our team has worked to fix it. As of now, the incident has been resolved, and webhooks should be able to be created successfully, and fire without errors. Let me know if I can address any additional concerns.

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