Devolutions/UniGetUI · warning · InvalidOperationException

Homebrew does not support installing arbitrary versions

Error message

Homebrew does not support installing arbitrary versions

What it means

Homebrew's GetInstallableVersions_UnSafe unconditionally throws InvalidOperationException. Homebrew installs the current formula/cask head and does not expose a selectable version catalog, so arbitrary-version listing is unsupported.

Source

Thrown at src/UniGetUI.PackageEngine.Managers.Homebrew/Helpers/HomebrewPkgDetailsHelper.cs:122

    protected override string? GetInstallLocation_UnSafe(IPackage package)
    {
        // Apple Silicon prefix is /opt/homebrew, Intel/Linux is /usr/local (or /home/linuxbrew).
        // Formulae live under Cellar/<name>, casks under Caskroom/<token>.
        foreach (var prefix in new[] { "/opt/homebrew", "/usr/local", "/home/linuxbrew/.linuxbrew" })
        {
            foreach (var kind in new[] { "Cellar", "Caskroom" })
            {
                var path = Path.Join(prefix, kind, package.Id);
                if (Directory.Exists(path))
                    return path;
            }
        }
        return null;
    }

    protected override IReadOnlyList<string> GetInstallableVersions_UnSafe(IPackage package)
        => throw new InvalidOperationException("Homebrew does not support installing arbitrary versions");
}

View on GitHub (pinned to 9b1d7d0eab)

Solutions

  1. Gate version requests on the capability flag for Homebrew.
  2. Install the current formula/cask without a version pin.
  3. Catch InvalidOperationException and surface only the installed version.

Example fix

// before
var versions = await pkg.GetInstallableVersionsAsync(); // throws for brew
// after
if (pkg.Manager.Capabilities.SupportsArbitraryVersions)
    versions = await pkg.GetInstallableVersionsAsync();
else
    versions = [pkg.Version];
Defensive patterns

Strategy: validation

Validate before calling

if (package.Manager.Capabilities.SupportsArbitraryVersions)
    versions = package.GetInstallableVersionsAsync();
else
    versions = new[] { package.Version };

Type guard

static bool CanListVersions(IPackage pkg) =>
    pkg.Manager.Capabilities.SupportsArbitraryVersions;

Prevention

When it happens

Trigger: Any code path requesting installable versions for a Homebrew package (version picker, pre-install resolution).

Common situations: UI version dropdown for a brew formula/cask; automation expecting a version list.

Related errors

AI-assisted analysis of Devolutions/UniGetUI@9b1d7d0eab (2026-08-13). Data as JSON: /api/errors/f9b4ffb290cc6ddb. Report an issue: GitHub.