Networking issue
jonas-admin
PROOP

3 months ago

We're experiencing an issue where if a request is forwarded by a reverse proxy (kong, hosted in a railway project) to an upstream service (hosted in another railway project), the response we're getting is:

{
  "status": "error",
  "code": 404,
  "message": "Application not found",
  "request_id": "Ry17M9MpQPWAG3Ck0ubPiw"
}

We tried to directly access the custom domain and, for good measure, a generated domain as well. The behavior is as follows:

Request -> Service (either via custom domain or generated) ... ✅

Request -> Kong (via custom domain) -> Service (either via custom domain or generated) ... ❌ (application not found)

This was known to be last working today around 12AM PST

Screenshot_2026-02-27_at_10.59.53_AM.png

Attachments

Solved

21 Replies

3 months ago

Please have kong strip the fastly-ff header.


jonas-admin
PROOP

3 months ago

will try


lightshire
PRO

3 months ago

this is also happening to us,

we have a nextjs proxy to an /api/

both are in railway, but having failure

image.png

Attachments


3 months ago

Please strip the fastly-ff header before making a request to the upstream.


lightshire
PRO

3 months ago

we dont have fastly-ff header on nextjs, how does this get removed?


3 months ago

It's an incoming header, delete it.


lightshire
PRO

3 months ago

Question, our clients are asking why suddenly this need to fix this?

do we have an incident report for this?

or is this part of the edge network incident this morning?


mathu97
PRO

3 months ago

we were getting 503s now we're getting these 404s ...


3 months ago

It's a new header that Fastly is sending.


dekodeveloper
FREE

3 months ago

Sameissuehere.Customdomainsreturning404"Applicationnotfound" since~6:10PMPST.Direct*.up.railway.app URLsworkfine.Alreadytriedredeployingandre-addingcustomdomainwithfreshCNAME+TXTverification(bothgreen).Region:us-west2.

https://station.railway.com/questions/custom-domains-returning-504-timeout-e-9b9ba1b2


jonas-admin
PROOP

3 months ago

{
  "method": "GET",
  "path": "/",
  "headers": {
    "host": "web1-dev.up.railway.app",
    "user-agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/145.0.0.0 Safari/537.36",
    "accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7",
    "accept-encoding": "gzip",
    "accept-language": "en-US,en;q=0.9",
    "backend_is_origin": "1",
    "cache-control": "no-cache",
    "cdn-loop": "Fastly",
    "fastly-client-ip": "180.190.225.237",
    "fastly-ff": "scJ4iSV4UkyHDI2juJNzrcUzYk/oO1PMCyYg4bz5Utg=!TYO!cache-tyo11947-TYO",
    "fastly-orig-accept-encoding": "gzip, deflate, br, zstd",
    "fastly-ssl": "1",
    "pragma": "no-cache",
    "priority": "u=0, i",
    "sec-ch-ua": "\"Chromium\";v=\"145\", \"Not:A-Brand\";v=\"99\"",
    "sec-ch-ua-mobile": "?0",
    "sec-ch-ua-platform": "\"macOS\"",
    "sec-fetch-dest": "document",
    "sec-fetch-mode": "navigate",
    "sec-fetch-site": "none",
    "sec-fetch-user": "?1",
    "upgrade-insecure-requests": "1",
    "x-edge-region": "Asia",
    "x-forwarded-for": "180.190.225.237, 167.82.139.47",
    "x-forwarded-host": "web1-dev.up.railway.app",
    "x-forwarded-proto": "https",
    "x-forwarded-server": "cache-tyo11947-TYO",
    "x-railway-edge": "railway/asia-southeast1-eqsg3a",
    "x-railway-request-id": "4D6qQA12Tl6_573HVOLIQQ",
    "x-real-ip": "167.82.139.47",
    "x-request-start": "1772161744984",
    "x-timer": "S1772161745.944717,VS0",
    "x-varnish": "3085425852"
  },
  "body": null
}

from an echo server we deployed (result from a direct call)


jonas-admin
PROOP

3 months ago

stripping the header does not work


jonas-admin
PROOP

3 months ago

applied these to test

Screenshot_2026-02-27_at_11.26.23_AM.png

Attachments


jonas-admin
PROOP

3 months ago

x-access-token got stripped but fastly-ff is still there


jonas-admin
PROOP

3 months ago

maybe, just maybe, the fastly headers are getting re-added at the upstream side (since the echo service is under a generated domain)


jonas-admin
PROOP

3 months ago

Kong can't strip the fastly headers at all


3 months ago

We are working on a fix that will strip fastly-ff on our Edge.


dekodeveloper
FREE

3 months ago

Update: Was planning to try stripping the fastly-ff header in our nginx gateway config (as suggested by @brody), but all our

custom domains just came back on their own (~7:56 PM PT). Looks like Railway resolved it on their end. All subdomains recovering

now.


3 months ago

Yep, see the above message. We now strip that header on our Edge.


jonas-admin
PROOP

3 months ago

Alright thanks


3 months ago

Sorry about that, everyone, this was just one of those incredibly ultra-niche things you really have no way of knowing about beforehand.


Status changed to Solved brody 3 months ago


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