canonical/multipass

[snapshot] Lack of interactive stdin causes unhandled exception on `multipass restore`

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#4825 opened on Apr 15, 2026

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buggood first issuelowlow hanging fruit

Description

Describe the bug I am trying to restore the state of a VM without interactive stdin. If the --destructive flag is not used, it results in an unhandled exception.

└─[2] echo "no" | multipass stop a             
└─[λ] echo "no" | multipass restore a.snapshot1
[2026-04-15T17:44:54.113] [error] [client] Caught an unhandled exception: Unable to query client for confirmation. Use '--destructive' to automatically discard current machine state.

To Reproduce How, and what happened?

  1. multipass launch -n a && multipass stop a
  2. multipass snapshot a
  3. echo "no" | multipass restore a.snapshot1

Expected behavior Multipass should handle the exception and output the error message to the user.

Additional info

  • OS: Ubuntu 24.04 (authd)
  • CPU architecture or model: amd64
  • multipass version: 1.17.0-dev

Contributor guide

Tech stack
cpp
Domain
cli
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic C++ knowledgeUnderstanding of CLI stdin handling
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
Examine the multipass restore command implementation in the client code (likely in src/client/ directory). The error 'Unable to query client for confirmation' suggests a missing check when stdin is not interactive. Look for where user confirmation is requested and handle the non interactive case gracefully, as done with destructive flag. The fix should catch the exception and output the error message instead of aborting.