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If an AppsFlyer server-to-server (S2S) event request for an iOS app returns HTTP 200 but the event does not appear, check the app ID in the request URL first. For this endpoint, AppsFlyer requires the App Store’s numeric ID with an id prefix, such as id123456789. Omitting that prefix can produce a 200 response without recording the event.
Correct the iOS app ID in the S2S URL
AppsFlyer’s S2S Send Event API v3 uses POST https://api3.appsflyer.com/inappevent/{app_id}. For iOS, replace {app_id} with id followed by the numeric App Store ID. For example, use /inappevent/id123456789, not /inappevent/123456789. AppsFlyer’s Send Event API reference says that leaving off the prefix can return 200 OK without recording the event.
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Check the final URL your integration actually sends, not only a configuration value or log entry from before URL construction. A successful HTTP status confirms a response, but AppsFlyer performs only minimum validation on receipt; its reference warns that an OK response does not guarantee the event was completely recorded.
Keep the S2S and iOS SDK ID formats separate
The required format depends on where the identifier is used. In the S2S URL path, the iOS App Store ID needs the id prefix. AppsFlyer’s iOS SDK troubleshooting guide uses a numeric-only app ID in its configuration guidance. These are different fields in different integration methods: do not remove the prefix from the S2S URL because of the SDK format, or add it to the SDK setting because the S2S path needs it.
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For an SDK-specific problem, use AppsFlyer’s iOS SDK troubleshooting guide. It identifies an app ID not found as a possible 404 cause and an authentication or dev-key issue as a possible 400 cause.
If the prefix is correct, check the rest of the request
A correct path does not establish that the rest of the request is valid. Check these S2S details against the v3 Send Event API reference:
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- App and credential match: Confirm that the app ID in the URL belongs with the S2S authentication key you send. AppsFlyer lists an app ID/token mismatch among bad-request causes and distinguishes an unauthorized response when the key is not that app’s S2S key.
- Required identifier: Make sure the JSON body includes
appsflyer_id, and verify that its value belongs to the intended user or device context. - JSON and event count: Validate that the body is well-formed JSON and correctly stringified by your client. Send one event per request rather than bundling multiple events in one body.
- Payload and transport: The documented JSON payload limit is 1 KB, and the connection must use TLS 1.2 or higher.
Verify recording independently of HTTP 200
After correcting the path or another request issue, check the event in the relevant AppsFlyer reporting or test workflow. Do not use the HTTP status alone as proof of ingestion: AppsFlyer explicitly documents that a 200 response may be returned even when the event is not fully recorded. If the event remains absent, inspect the actual URL, request body, authentication header, app-to-key pairing, and reporting evidence together; the status code cannot identify which of those is still wrong.
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