902 Official

Device Already Installed

The device serial has already been initialized and an active cmcKey exists.

Likely Causes

Re-running initialization on an already-active device
Redeploying without persisting the original cmcKey

Fix

This is idempotent — not a hard failure, but the 902 response does NOT return the cmcKey: verified live against the KRA sandbox (2026-07-04), the body is {"resultCd":"902","resultMsg":"This device is installed","data":null}. Use the cmcKey you persisted at first initialization. If it is lost, contact timsupport@kra.go.ke to de-register the serial so the device can be re-initialized — there is no self-service recovery.

Gotcha

The cmcKey is issued exactly once, only in the original init response, with no rotation mechanism — 902 will not hand it back. Any log line recording the full init response permanently leaks this key; redact cmcKey before any logging. Also watch for a present-but-empty cmcKey file after a failed restore: a file-exists check passes, but every subsequent request fails with 899/900 — validate the file is non-empty.

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