Hi everyone, I'm facing a critical issue with my Vapi.ai voice assistant integration with n8n webhooks. When the voice assistant triggers a tool, the webhook call fails, and I consistently get the error {"message":"header name must be a non-empty string"} in the Vapi.ai webhook logs. Interestingly, manual tests of the same tool within the Vapi.ai interface work perfectly, and my n8n webhook also functions correctly when tested directly with external tools. This suggests the problem lies with how Vapi.ai generates HTTP headers when the tool is triggered by the voice assistant, possibly inserting a malformed or empty header. Has anyone else encountered this specific header name must be a non-empty string error when using Vapi.ai with n8n, especially when triggered by the voice assistant? If so, were you able to find a solution or a workaround? Any insights would be greatly appreciated!

Replace the direct tool webhook call with a custom HTTP or MCP node in your Vapi assistant flow, where you manually define headers, this avoids the empty header issue..