Reddit Conversions API Errors: Every Code, Message, and Fix
Reddit Conversions API errors come in five families, and Reddit documents each with the exact message and the exact fix - which makes diagnosis unusually mechanical: read the response, look up the family, apply the one fix that belongs to it. This guide walks all five families the way the official error handling reference lays them out, with the working practice for each.
The Complete Error Table
| Response | Reddit's message | What it means | The documented fix |
|---|---|---|---|
| 400 | "There were {Number} invalid conversion events. None were processed." | The payload violates CAPI v3 validation rules | Pass valid event values |
| 400 | "Bad Request" - "The maximum allowable events are 1000 events/call." | Batch above the cap | Split events across multiple calls |
| 401 | "No bearer token provided" | The Authorization header is missing | Pass the token properly |
| 401 | "UNAUTHORIZED" | The token is invalid and cannot be authenticated | Create a valid access token |
| 403 | "You're not authorized to post conversions to Pixel ID {Pixel ID}." | The account lacks posting rights on that pixel | Use a token with adequate permission and the correct Pixel ID |
| 403 | "Missing adsconversions scope to post conversions to Pixel." | The developer app lacks the required scope | Add adsconversions to your scope |
| 429 | "Your user agent was automatically ratelimited." | Default user agents get throttled | Set a unique, descriptive user-agent header |
| 429 | "Too many requests/events within timeframe." | The rate-limiting quota for the window is exhausted | Back off and batch (see the 429 section) |
| 500 | "The service is currently unavailable. No conversion events were processed." | Service downtime | Retry posting conversion events later |
Two 400 cases deserve a second look. The invalid-events message says none were processed - one malformed event out of a thousand fails the entire request, so a batch that half-succeeded did not succeed at all. Reddit also points v2 migrators at the fields that changed: event_type.tracking_type and event_metadata moved between versions, and a v2-shaped payload inside a v3 endpoint produces exactly this response.
The 429 Family: How Reddit Wants You to Retry
Reddit splits its rate-limit responses into two causes. The first is self-inflicted: default user agents - the strings HTTP libraries send by default - may lead to throttling, so the reference asks for a unique, descriptive user-agent header identifying your integration. The second is genuine quota exhaustion, and for it Reddit prescribes three moves in order:
- Cache data locally or store it in a database instead of polling the API.
- Consider sending backfill data in batches.
- Set retry logic that limits retry frequency through exponential backoff.
The platform ceilings behind these responses are generous for a single funnel - 1,000 requests per second, 10,000 events per second, 1,000 events per request - so a 429 on a normal funnel usually means a retry loop without backoff, not real volume. Where the limits come from and how batching fits them is in the events and parameters guide.
Reading the Message Before Touching the Config
The diagnostic order follows the table. A 400 points at field values - check tracking_type and the metadata object against the v3 schema, and check the batch size. A 401 points at the token itself - missing header or an invalid value, fixed in the credentials screen. A 403 points at permissions: the token works, but not for that Pixel ID, or the developer app lacks the adsconversions scope. A 429 points at pacing, and a 500 at Reddit's side - nothing in your config is wrong.
Token-side failures (401 and 403) and their fixes are mapped credential-by-credential in the Reddit conversion access token guide, which covers both generation and storage - the failure a wrong Pixel ID produces is the 403 family. For a one-off manual send while you debug, the free Pixel Activator builds valid test events without a pipeline. The cluster overview is in the complete guide, and the setup path that produces a working first request is Reddit Conversions API setup.