`vehicleRentalStations` query intermittently returns empty array

[baleboy]

Note: I'm not sure if this is the right place to report this, if not I apologise and would appreciate it if you could let me know where to report.

Endpoint

POST https://api.digitransit.fi/routing/v2/hsl/gtfs/v1

Summary

The vehicleRentalStations GraphQL query intermittently returns an empty array ({"data":{"vehicleRentalStations":[]}}) on roughly 40–50% of requests, while other requests to the same endpoint return the full list of 455 stations. Both response types are HTTP 200 with identical headers — there is no error, no rate-limit signal, and no GraphQL errors field.

Reproduction

Run 20 sequential identical requests:

API_KEY="<your-key>"
URL="https://api.digitransit.fi/routing/v2/hsl/gtfs/v1?digitransit-subscription-key=$API_KEY"
for i in $(seq 1 20); do
  curl -s -X POST "$URL" -H "Content-Type: application/graphql" \
    -d '{ vehicleRentalStations { stationId } }' \
  | python3 -c "import json,sys; print(len(json.load(sys.stdin)['data']['vehicleRentalStations']))"
done

Observed result (20 sequential requests, ~5 seconds)

455, 455, 455, 455, 0, 455, 0, 0, 455, 0,
455, 455, 0, 0, 0, 0, 0, 0, 0, 455

9/20 returned 0 stations, 11/20 returned 455. Failures cluster but are not deterministic — re-running the script produces a different distribution.

Expected result

All 20 requests should return 455 stations.

Failing response (full)

HTTP/2 200
date: Tue, 07 Apr 2026 04:59:16 GMT
content-type: application/json
content-length: 37
vary: Accept,Accept-Encoding,Accept-Language
access-control-allow-credentials: false

{"data":{"vehicleRentalStations":[]}}

Successful response (headers)

HTTP/2 200
date: Tue, 07 Apr 2026 04:59:16 GMT
content-type: application/json
vary: Accept,Accept-Encoding,Accept-Language
access-control-allow-credentials: false

(body: 455 stations, ~57 KB)

The failing and succeeding responses are issued at the same second with identical headers (modulo content-length). There is no GraphQL errors array in the failing response — it is a structurally valid empty result.

Same issue with single-station query

The single-station query vehicleRentalStation(id: "smoove:900") exhibits the same intermittent failure: it returns null for the same station ID that returned valid data on the previous request, with no error message.

20 sequential requests for smoove:900:

null, 5 bikes / 15 spaces, null, 5 bikes / 15 spaces, 5 bikes / 15 spaces,
5 bikes / 15 spaces, null, null, null, null,
null, null, 5 bikes / 15 spaces, 5 bikes / 15 spaces, null,
null, null, 5 bikes / 15 spaces, 5 bikes / 15 spaces, 5 bikes / 15 spaces

11/20 returned null, 9/20 returned data.

Failing response:

HTTP/2 200
date: Tue, 07 Apr 2026 05:02:00 GMT
content-type: application/json
content-length: 38
vary: Accept,Accept-Encoding,Accept-Language
access-control-allow-credentials: false

{"data":{"vehicleRentalStation":null}}

The station unambiguously exists (other requests in the same second return its data). This rules out a "station not found" interpretation of the null response.

Other queries on the same endpoint are not affected

The stops query was tested 3 times in a row and returned 8334 stops every time. The issue appears to be specific to vehicle rental queries.

stops request 1: 8334 results
stops request 2: 8334 results
stops request 3: 8334 results

Environment

• Date observed: 2026-04-07
• API endpoint: https://api.digitransit.fi/routing/v2/hsl/gtfs/v1
• Subscription key tier: standard developer key
• Tested from: macOS, curl/8.7.1 over IPv4
• Issue is reproducible from any machine — it is server-side.