Troubleshooting

Command not found / backend missing

Symptoms: "unsupported" or "backend not found" errors.

Actions:

• Run fur doctor.
• Verify required tools for the target source: nix, flatpak, dpkg-deb, steam-run, appimage-run.

System operation failures

Symptoms: rebuild or rollback failure messages.

Actions:

• fur system doctor --json
• Verify sudo policy.
• Run fur system repair when marker health is invalid.

Flatpak failures

Symptoms: install / search / list / info failures.

Actions:

• Verify the remote list.
• Set the remote explicitly with --remote.
• Inspect the typed error category — not-found, permission, already-installed, remote-unreachable.

Kit verification failures

Symptoms: signature / pin / attestation mismatch.

Actions:

• Confirm the trust keyring path and signer IDs.
• Confirm the trust + pin policy environment values.
• Use the attestation override only in a controlled migration.

Apt compatibility failures

Symptoms: behaviour differs from Ubuntu apt scripts.

Actions:

• Consult UBUNTU-COMPAT.md in the source tree.
• Use --json + branch on schema/action in automation.