Unity-Technologies/UnityCsReference · error · ArgumentException

'{standaloneSubtarget}' is not a valid subtarget for the Sta

Error message

'{standaloneSubtarget}' is not a valid subtarget for the Standalone build target

What it means

When resolving a NamedBuildTarget for a Standalone target from a subtarget integer, only Player and Server are accepted. Any other StandaloneBuildSubtarget enum value hits the default case and throws ArgumentException.

Source

Thrown at Editor/Mono/BuildPipeline/NamedBuildTarget.cs:192

            }

            return NamedBuildTarget.FromBuildTargetGroup(buildTargetGroup);
        }

        internal static NamedBuildTarget FromTargetAndSubtarget(BuildTarget target, int subtarget)
        {
            var buildTargetGroup = BuildPipeline.GetBuildTargetGroup(target);
            if (buildTargetGroup == BuildTargetGroup.Standalone)
            {
                var standaloneSubtarget = (StandaloneBuildSubtarget)subtarget;
                switch (standaloneSubtarget)
                {
                    case StandaloneBuildSubtarget.Player:
                        return NamedBuildTarget.Standalone;
                    case StandaloneBuildSubtarget.Server:
                        return NamedBuildTarget.Server;
                    default:
                        throw new ArgumentException($"'{standaloneSubtarget}' is not a valid subtarget for the Standalone build target");
                }
            }

            return NamedBuildTarget.FromBuildTargetGroup(buildTargetGroup);
        }

        [ExcludeFromDocs]
        public static bool operator==(NamedBuildTarget lhs, NamedBuildTarget rhs)
        {
            return lhs.Equals(rhs);
        }

        [ExcludeFromDocs]
        public static bool operator!=(NamedBuildTarget lhs, NamedBuildTarget rhs)
        {
            return !lhs.Equals(rhs);
        }

View on GitHub (pinned to 225b0fbdb5)

Solutions

Ensure the subtarget passed is StandaloneBuildSubtarget.Player or StandaloneBuildSubtarget.Server.
If a new subtarget was added, extend the switch to map it to a NamedBuildTarget.
Use NamedBuildTarget.FromActiveSettings(target) which derives the correct subtarget from active settings.

Example fix

// before
var nbt = NamedBuildTargetInternal.GetNamedBuildTarget(target, rawSubtarget);

// after
var sub = (StandaloneBuildSubtarget)rawSubtarget;
if (sub != StandaloneBuildSubtarget.Player && sub != StandaloneBuildSubtarget.Server)
    throw new ArgumentOutOfRangeException(nameof(rawSubtarget), sub, "Only Player/Server standalone subtargets are supported.");
var nbt = NamedBuildTargetInternal.GetNamedBuildTarget(target, rawSubtarget);

Defensive patterns

Strategy: validation

Validate before calling

var sub = (StandaloneBuildSubtarget)subtarget;
if (sub != StandaloneBuildSubtarget.Player && sub != StandaloneBuildSubtarget.Server)
    throw new ArgumentOutOfRangeException(nameof(subtarget), sub, "Only Player/Server subtargets are valid for Standalone.");

Type guard

static bool IsValidStandaloneSubtarget(int sub) =>
    Enum.IsDefined(typeof(StandaloneBuildSubtarget), sub) &&
    ((StandaloneBuildSubtarget)sub is StandaloneBuildSubtarget.Player or StandaloneBuildSubtarget.Server);

Prevention

Only pass Player or Server subtargets for Standalone builds.
Use FromActiveSettings(target) to avoid manual subtarget handling.

When it happens

Trigger: Calling the internal GetNamedBuildTarget(target, subtarget) where the target is in the Standalone group and the subtarget integer casts to a StandaloneBuildSubtarget value other than Player (0) or Server (1).

Common situations: A future StandaloneBuildSubtarget enum member added without updating this switch; passing a raw subtarget integer that does not correspond to a valid member; platform extension injecting a custom standalone subtarget.

Related errors

AI-assisted analysis of Unity-Technologies/UnityCsReference@225b0fbdb5 (2026-08-13). Data as JSON: /api/errors/83b173b4ed91112b. Report an issue: GitHub.