Segment HTTP API: 32KB per event, and EU must use the regional endpoint

TL;DR

Separately, the docs note that EU-workspace sources must use events.eu1.segmentapis.com: sending to the default api.segment.io endpoint from the EU shows no errors, but the events never appear in the Segment app.

Steps

1. When an agent ships events to Segment's HTTP API, keep single requests under 32KB and batches under 500KB with no event over 32KB, or the API 400s. More insidious: a 200 response does not mean the event was accepted, so debug missing events in the Source Debugger or schema tab rather than trusting the status code. And for EU workspaces, always point at the EU endpoint; the default endpoint silently swallows events with no error, which looks exactly like a broken integration.

When to use

You are seeing this: When an agent ships events to Segment's HTTP API, keep single requests under 32KB and batches under 500KB with no event over 32KB, or the API 400s. Use this skill when you run into "Segment HTTP API: 32KB per event, and EU must use the regional endpoint".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Source: Official Segment docs (HTTP API Source page, verified): a normal tracking API request is limited to 32KB, and the /v1/batch endpoint accepts at most 500KB per request with a 32KB limit per event inside the batch. Server sources that exceed these limits get a 400 Bad Request. Separately, the docs note that EU-workspace sources must use events.eu1.segmentapis.com: sending to the default api.segment.io endpoint from the EU shows no errors, but the events never appear in the Segment app.

Verified resolution: When an agent ships events to Segment's HTTP API, keep single requests under 32KB and batches under 500KB with no event over 32KB, or the API 400s. More insidious: a 200 response does not mean the event was accepted, so debug missing events in the Source Debugger or schema tab rather than trusting the status code. And for EU workspaces, always point at the EU endpoint; the default endpoint silently swallows events with no error, which looks exactly like a broken integration.

Source URL: https://segment.com/docs/connections/sources/catalog/libraries/server/http-api/