---
lastModified: 2026-09-10
title: "This factor can't be changed with a single value here."
description: "Simulation interventions, failed runs, and handing fixes to Runner. Exact Runner messages, recovery steps, and checks for the completed result."
---

`This factor can't be changed with a single value here.` means the selected factor is not supported by the single-value intervention control. Choose a supported factor, such as headline, caption, visual style, or duration. Do not keep submitting a different text value for the same unsupported factor. Confirm a new prediction appears after an accepted change.

`Didn't finish: {message}` records the actual failure detail from the simulation request. Read that detail and correct a named input problem before retrying. Check for an existing run and its status first; this generic message does not say which stage failed or whether a run was created. If the detail offers no safe action, send Runner the run/session identifier and the full visible message.

`We couldn't hand this to Runner — nothing was sent. Try again.` means creating the recommendation handoff failed. Retry from the recommendation and confirm it appears in the destination chat. `We couldn't open the chat with Runner — try again.` happens after handoff creation succeeded but opening the chat failed: check the existing handoff and chats before creating another one. Do not assume a fix ran merely because the handoff exists.

For `We couldn't start the re-test — try again.`, inspect the recommendation's existing re-test/run state before retrying. Recovery means the intended re-test appears and eventually has results; it is not proven by a successful click. Escalate persistent failures with the original run, recommendation, and re-test identifiers.

For repeated failures, see [what to send Runner](/en/guides/help-and-reference/error-playbook-store-and-apps).