A 404 from nimble tasks results usually means you passed the crawl id instead of a task id. Crawls are two-level: nimble crawl status --id [crawl-id] returns per-page task ids (task-456, task-789), and nimble tasks results --task-id only accepts those. Pass the crawl id and you get a 404. And do not trust 'failed' in crawl status blindly - the reference says it occasionally misreports succeeded tasks as failed, so always try fetching the task results anyway before treating it as a failure.

Context: Nimble's own error-handling reference (nimbleway/agent-skills, error-handling.md): '404 from nimble tasks results' is caused by using the crawl_id instead of task_id - use the per-page task_ids from nimble crawl status, not the crawl job id. Related: crawl status may misreport task statuses as failed when they succeeded, so always try nimble tasks results --task-id before assuming failure.