# E016 — Unsupported OTLP protocol (https://jackin.tailrocks.com/reference/errors/E016/)



**E016**: Unsupported OTLP protocol

jackin' exports run telemetry over OTLP/gRPC only. This error means an OTLP endpoint is configured (`OTEL_EXPORTER_OTLP_ENDPOINT` or a per-signal variant) while `OTEL_EXPORTER_OTLP_PROTOCOL` (or a per-signal `_PROTOCOL` variable) requests a transport jackin' does not speak — typically `http/protobuf` or `http/json`. Rather than build an exporter that would silently never deliver, jackin' stops at startup.

## What to try [#what-to-try]

* Set `OTEL_EXPORTER_OTLP_PROTOCOL=grpc` (the default for backends such as Parallax) and point `OTEL_EXPORTER_OTLP_ENDPOINT` at the gRPC endpoint, e.g. `http://localhost:4317`.
* Or unset the OTLP endpoint variables to disable export — jackin' then records the run to a local diagnostics file instead.

## See also [#see-also]

* [Run Telemetry](/guides/run-telemetry/) — how to configure OTLP export and where a run is recorded.
* Pass `--debug` to any `jackin` command to enable diagnostic tracing.