# X_ERROR_RETRY_INVALID

## Means

error retry classification is unknown or already claimed

## Typical cause

`registerErrorRetry()` given a kind that is not `terminal`, `retryable` or `retry-after`, or a second, different classification for one code. Core's own codes are closed to reclassification: an app that could call `X_DRAINING` terminal would stop the retry a rolling restart depends on

## Fix

`x errors list --json` — then `registerErrorRetry({ <CODE>: 'retryable' })` with one of `terminal`, `retryable`, `retry-after`

[Core and runtime](/error-codes#core-and-runtime)