# X_MAIL_KEY_MISSING

## Means

a mail rendered a key or slot with no value in its locale

## Typical cause

send() resolved a catalog key the locale does not define, a catalog value still holding a placeholder, or a {slot} with no value, so nothing left

## Fix

`x i18n sync <locale>` — then translate the keys in meta.keys

[Mail](/error-codes#mail)