WARP client version 2024.12.554.0 fails to connect to WARP

Zero Trust WARP
1

What is the name of the domain?

connectivity.cloudflareclient.com

What is the error message?

CF_HOST_UNREACHABLE_CHECK: The initial connectivity check failed because the host was unreachable.

What is the issue you’re encountering

After upgrading WARP client to version 2024.12.554.0 it fails to connect.

What steps have you taken to resolve the issue?

Rolling back to version 2024.11.309.0 restores connectivity.

What are the steps to reproduce the issue?

Install version 2024.12.554.0 and attempt to use gateway only without DNS mode on an IPv4 only network.

connectivity.txt log:

====================================================================
Tunnel Endpoint

unknown

====================================================================
DNS Resolution

Inside Tunnel

Resolved ‘connectivitycloudflareclientcom’ to:
- 162.159.138.65:0
- 162.159.137.65:0
- [2606:4700:7::a29f:8941]:0
- [2606:4700:7::a29f:8a41]:0

====================================================================
Trace Result

Inside Tunnel

Trace ‘connectivitycloudflareclientcom’ via 162.159.138.65:
fl=98f199
h=connectivitycloudflareclientcom
ip=8.53.167.101
ts=1734712893.106
visit_scheme=https
uag=
colo=DEN
sliver=none
http=http/1.1
loc=US
tls=TLSv1.3
sni=plaintext
warp=off
gateway=off
rbi=off
kex=P-256

Trace ‘connectivitycloudflareclientcom’ via 162.159.137.65:
fl=711f15
h=connectivitycloudflareclientcom
ip=8.53.167.101
ts=1734712893.155
visit_scheme=https
uag=
colo=DEN
sliver=none
http=http/1.1
loc=US
tls=TLSv1.3
sni=plaintext
warp=off
gateway=off
rbi=off
kex=P-256

Error Tracing ‘connectivitycloudflareclientcom’ via 2606:4700:7::a29f:8941:
reqwest::Error { kind: Request, url: “cloudflare connectivity trace url”, source: hyper_util::client::legacy::Error(Connect, ConnectError(“tcp connect error”, Os { code: 10051, kind: NetworkUnreachable, message: “A socket operation was attempted to an unreachable network.” })) }

Error Tracing ‘connectivitycloudflareclientcom’ via 2606:4700:7::a29f:8a41:
reqwest::Error { kind: Request, url: “cloudflare connectivity trace url”, source: hyper_util::client::legacy::Error(Connect, ConnectError(“tcp connect error”, Os { code: 10051, kind: NetworkUnreachable, message: “A socket operation was attempted to an unreachable network.” })) }

Outside Tunnel

Trace ‘engagecloudflareclientcom’ via 162.159.36.1:
fl=98f157
h=engagecloudflareclientcom
ip=8.53.167.101
ts=1734712893.178
visit_scheme=https
uag=
colo=DEN
sliver=none
http=http/1.1
loc=US
tls=TLSv1.3
sni=plaintext
warp=off
gateway=off
rbi=off
kex=P-256

Error Tracing ‘engagecloudflareclientcom’ via 2606:4700:4700::1111:
reqwest::Error { kind: Request, url: “cloudflare connectivity trace url”, source: hyper_util::client::legacy::Error(Connect, ConnectError(“tcp connect error”, Os { code: 10051, kind: NetworkUnreachable, message: “A socket operation was attempted to an unreachable network.” })) }

3

Hello everyone, I rolled back to version 492, everything connected, but it doesn’t connect to version 554

4

In my specific situation, rolling back to 492 doesn’t resolve the problem; only rolling back to 309 does.

5

I have the same issue
Windows version 2024.12.554.0 is broken, client fails to connect when using the version
it works if you rollback to an older version

6

release notes Zero Trust WARP Client Changelog · Cloudflare Zero Trust docs

mention following - however disconnecting/reconnecting or removing a custom dns server from primary network interface does not help

Known issues:

DNS resolution may be broken when all of the following conditions are true:
    WARP is in Secure Web Gateway without DNS filtering (tunnel-only) mode.
    A custom DNS server address is configured on the primary network adapter.
    The custom DNS server address on the primary network adapter is changed while WARP is connected.

To work around the DNS issue, reconnect the WARP client by toggling off and back on
7

In my situation this would never resolve - looking at the logs the issue seemed to be that this specific mode is expecting to be able to connect over ipv6 and if it isn’t then the connection fails.