X_DB_GEN_FAILED
Means
the x db step failed for a reason no framework error claimed
Typical cause
a write the filesystem refused, the database unreachable. A failure the engine itself names — X_MIGRATION_CONFLICT, X_MIGRATION_IRREVERSIBLE, X_DB_UNAVAILABLE — reaches you as that code, with its own fix, never wrapped in these
Fix
read cause — it carries the underlying error verbatim — then x doctor --json