Troubleshoot and debug
Troubleshoot and debug errors commonly associated with Workers VPC.
Workers VPC may return errors at runtime when connecting to private services through Cloudflare Tunnel.
| Error Message | Details | Recommended fixes |
|---|---|---|
Error: ProxyError: dns_error | DNS resolution failed when attempting to connect to your private service through the tunnel. | This error may occur if your cloudflared version is outdated. Ensure you are running cloudflared version 2025.7.0 or later (latest version recommended). See Cloudflare Tunnel update instructions. |
Error: ProxyError: dns_error | Cloudflare Tunnel may be configured with http2 protocol (TUNNEL_TRANSPORT_PROTOCOL:http2), which works for Cloudflare Zero Trust (see note) traffic but prevents DNS resolution from Workers VPC. | Workers VPC requires Cloudflare Tunnel to connect using the QUIC transport protocol. Ensure outbound UDP traffic on port 7844 is allowed through your firewall. |
| Requests not staying within VPC | Worker requests using .fetch() with a public hostname are routing out of the VPC to the hostname configured for the VPC Service. | Ensure your Worker code and the VPC Service use the internal VPC hostname for backend services, not a public hostname. |
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