3 months ago
The X-Railway-Fallback: true header and "Application not found" response indicate the request is hitting Railway's edge but not being routed to the service correctly.
Unfortunately, I don't have direct access to Railway's edge routing configuration or certificate provisioning systems through my available tools.
This is a backend infrastructure issue that requires Railway support team intervention.
- Here are the info :
- Custom domain ID:
8a5177d4-5d17-4ae7-b4b9-2166d58097ae - Domain:
api.custoomi.com - Service:
custoomi-production - The fact that the Railway subdomain works (
1oda8p1o.up.railway.app) but the custom domain doesn't - The
X-Railway-Fallback: trueheader you're seeing - Certificate status is stuck at
CERTIFICATE_STATUS_TYPE_VALIDATING_OWNERSHIP
- Custom domain ID:
The certificate validation status is a red flag, it may be blocking the edge from properly routing traffic. How can I ask if the support team can check:
- Whether the certificate provisioning completed
- If there's a routing misconfiguration on the edge
- Any logs from the edge that show why requests are falling back
This is beyond what I can diagnose from my end. The support team has the tools to investigate the edge infrastructure directly but they are unreachable without enterprise plan... If anybody knows this kind of issue.. Thx !
1 Replies
Status changed to Awaiting Railway Response Railway • 3 months ago
2 months ago
The X-Railway-Fallback: true header means the request is reaching Railway’s edge network but the edge cannot find a matching route for the custom domain, so it returns the fallback response “Application not found.”
Since your Railway subdomain (1oda8p1o.up.railway.app) works correctly, the service itself is running. The issue is almost always related to DNS configuration or certificate validation for the custom domain.
One important clue is that the certificate status is stuck at:
CERTIFICATE_STATUS_TYPE_VALIDATING_OWNERSHIP
When the certificate ownership validation does not complete, Railway cannot fully attach the domain to the service at the edge, which causes the request to fall back.
Things to verify:
1. DNS record configuration
Make sure the DNS record for api.custoomi.com is correctly pointing to Railway.
For most setups it should be a CNAME:
api.custoomi.com → 1oda8p1o.up.railway.appAvoid using an A record pointing elsewhere.
2. DNS propagation
After adding or changing the record, it may take time for Railway’s certificate validation to detect the record. You can check with:
dig api.custoomi.comThe result should resolve to the Railway domain.
3. Remove and re-add the custom domain
If the certificate is stuck in validating ownership, removing the domain from the Railway service and adding it again can trigger a fresh certificate provisioning attempt.
4. Verify the domain is attached to the correct service
Make sure api.custoomi.com is attached to the custoomi-production service and not another environment or project.
In most cases, once DNS resolves correctly and the certificate moves to ISSUED, the X-Railway-Fallback: true header disappears and the domain begins routing to the service normally.
So the issue is typically certificate validation + DNS alignment, not a problem with the running service itself.