Installation failed but your previous installation was resto

Error message

Installation failed but your previous installation was restored

What it means

On Linux, after copying the new but binary into ~/.local/bin and chmod 755, install_linux runs 'but --version' to validate it. When that fails but a backup of the previous binary exists, the backup is renamed back and re-validated; if the restored copy passes, the installer bails with this message. Your previous version is intact and functional - the new one was rejected post-install.

Source

Thrown at crates/but-installer/src/install_linux.rs:117

    // NOTE: Must copy rather than rename. Rename assumes source and dest are on the same mount
    // point, but /tmp on Linux systems is very often an in-memory file system (tmpfs) and thus on
    // a different mount point than persistent files
    fs::copy(but_path, &install_bin_path)?;

    let mut perms = fs::metadata(&install_bin_path)?.permissions();
    perms.set_mode(0o755);
    fs::set_permissions(&install_bin_path, perms)?;

    if !validate_installed_binary(&install_bin_path) {
        warn("Final installation verification failed");

        if let Some(but_backup) = but_backup {
            warn("Attempting to restore backup");
            fs::rename(&but_backup, &install_bin_path)?;

            if validate_installed_binary(&install_bin_path) {
                info("Backup restored successfully, exiting ...");
                bail!("Installation failed but your previous installation was restored");
            } else {
                bail!(
                    "Installation failed and backup restoration also failed - 'but' command may not work"
                );
            }
        } else {
            bail!("Installation failed and no backup available to restore");
        }
    } else if let Some(but_backup) = but_backup {
        info(&format!(
            "Removing backup at {}",
            but_backup.to_string_lossy()
        ));
        fs::remove_file(&but_backup)?;
    }

    Ok(())
}

View on GitHub (pinned to caf1f223d3)

Solutions

Confirm the old version still works: ~/.local/bin/but --version
Diagnose why the new binary fails: run it directly from a temp dir and read the loader error ('No such file or directory' from ld.so means the ELF interpreter/libs are too new for the host)
Check mount flags (findmnt ~/.local/bin -o OPTIONS) for noexec and disk space (df -h ~/.local /tmp)
Stay on the last compatible version or upgrade the OS / build but from source

Defensive patterns

Strategy: fallback

Validate before calling

// Pre-flight: the host must be able to load the new binary's shared libraries
let out = std::process::Command::new("ldd").arg(&downloaded_but).output()?;
let ldd = String::from_utf8_lossy(&out.stdout);
if ldd.contains("not found") {
    anyhow::bail!("host is missing shared libraries required by the new but binary");
}

Try / catch

match but_installer::run_installation_with_version(request, false) {
    Err(e) if e.to_string().contains("previous installation was restored") => {
        // system is functional on the old version; report and stop, do not retry blindly
        log::warn!("update rejected; previous but version is still active");
    }
    result => result,
}

Prevention

Verify the host glibc/arch can run new artifacts before updating (ldd, uname -m)
Keep free disk space under ~/.local and /tmp
Allowlist ~/.local/bin/but with endpoint security before scripted updates

When it happens

Trigger: The newly downloaded binary fails to execute on this host - glibc older than the binary's requirements, wrong architecture, noexec mount on ~/.local/bin, truncated copy from a full disk, or endpoint security blocking newly written executables - while the previous binary still runs fine.

Common situations: Updating but on an old LTS distro (CentOS 7, Ubuntu 18.04) when a release raises its glibc baseline; corporate antivirus quarantining the new binary; ~/.local partition full during the copy.

Related errors

AI-assisted analysis of gitbutlerapp/gitbutler@caf1f223d3 (2026-08-20). Data as JSON: /api/errors/6f516a9ac85caaba. Report an issue: GitHub.