bytedance/deer-flow · error · HTTPException

Selected history entry has no previous content to roll back

Error message

Selected history entry has no previous content to roll back to

What it means

Error "Selected history entry has no previous content to roll back to" thrown in bytedance/deer-flow.

Source

Thrown at backend/app/gateway/routers/skills.py:373

    except Exception as e:
        logger.error("Failed to read history for %s: %s", skill_name, e, exc_info=True)
        raise HTTPException(status_code=500, detail=f"Failed to read history: {str(e)}")


@router.post("/skills/custom/{skill_name}/rollback", response_model=CustomSkillContentResponse, summary="Rollback Custom Skill")
async def rollback_custom_skill(skill_name: str, body: SkillRollbackRequest, request: Request, config: AppConfig = Depends(get_config)) -> CustomSkillContentResponse:
    await require_admin_user(request, detail=_ADMIN_REQUIRED_DETAIL)
    try:
        storage = _get_user_skill_storage(config)
        if not storage.custom_skill_exists(skill_name) and not storage.get_skill_history_file(skill_name).exists():
            raise HTTPException(status_code=404, detail=f"Custom skill '{skill_name}' not found")
        history = storage.read_history(skill_name)
        if not history:
            raise HTTPException(status_code=400, detail=f"Custom skill '{skill_name}' has no history")
        record = history[body.history_index]
        target_content = record.get("prev_content")
        if target_content is None:
            raise HTTPException(status_code=400, detail="Selected history entry has no previous content to roll back to")
        storage.validate_skill_markdown_content(skill_name, target_content)
        static_findings = await _scan_static_skill_markdown_or_raise(skill_name, target_content, app_config=config)
        scan = await scan_skill_content(target_content, executable=False, location=f"{skill_name}/{SKILL_MD_FILE}", app_config=config, static_findings=static_findings)
        skill_file = storage.get_custom_skill_file(skill_name)
        current_content = skill_file.read_text(encoding="utf-8") if skill_file.exists() else None
        history_entry = {
            "action": "rollback",
            "author": "human",
            "thread_id": None,
            "file_path": SKILL_MD_FILE,
            "prev_content": current_content,
            "new_content": target_content,
            "rollback_from_ts": record.get("ts"),
            "scanner": {"decision": scan.decision, "reason": scan.reason, "static_findings": static_findings},
        }
        if scan.decision == "block":
            await asyncio.to_thread(storage.append_history, skill_name, history_entry)
            raise HTTPException(status_code=400, detail=f"Rollback blocked by security scanner: {scan.reason}")

View on GitHub (pinned to 1dd6ba1acb)

Solutions

1. Choose a history entry that has previous content (not the earliest snapshot).
2. Save a new version of the skill first, then roll back to it.

When it happens

Trigger: Thrown at backend/app/gateway/routers/skills.py:373 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of bytedance/deer-flow@1dd6ba1acb (2026-08-14). Data as JSON: /api/errors/3231154e33e5dc7f. Report an issue: GitHub.