OrchardCMS/OrchardCore · error · NotSupportedException

The syntax isn't supported for IfElseTask.

Error message

The syntax {Syntax} isn't supported for IfElseTask.

What it means

IfElseTask evaluates its condition by switching on the activity's Syntax. Only Liquid (LiquidCondition) and JavaScript (Condition) evaluation are implemented; any other WorkflowScriptSyntax value hits the default arm and throws NotSupportedException, so the workflow branch cannot be decided.

Solutions

  1. Set Syntax to WorkflowScriptSyntax.Liquid and put the boolean condition in the LiquidCondition field.
  2. Or set Syntax to WorkflowScriptSyntax.JavaScript and provide the boolean condition in the Condition field.
  3. Repair the stored workflow definition if it contains a legacy/invalid syntax value.
  4. If a new syntax member exists in the enum, rebuild/update OrchardCore.Workflows so the switch arm is implemented.

Example fix

// before
var ifElse = new IfElseTask(); // Syntax unset -> unsupported
// after
var ifElse = new IfElseTask
{
    Syntax = WorkflowScriptSyntax.JavaScript,
    Condition = new JavaScriptExpression { Expression = "inputs.get('count') > 0" }
};
Defensive patterns

Strategy: validation

Validate before calling

// before running the workflow
if (ifElseTask.Syntax is not (WorkflowScriptSyntax.Liquid or WorkflowScriptSyntax.JavaScript))
    throw new InvalidOperationException($"IfElseTask requires Liquid or JavaScript syntax; got {ifElseTask.Syntax}");

Type guard

static bool IsSupportedSyntax(WorkflowScriptSyntax s) => s is WorkflowScriptSyntax.Liquid or WorkflowScriptSyntax.JavaScript;

Try / catch

try { result = await activity.ExecuteAsync(workflowContext, activityContext); }
catch (NotSupportedException ex) { logger.LogError(ex, "IfElseTask condition evaluation failed for syntax {Syntax}", syntax); /* route to error outcome */ }

Prevention

When it happens

Trigger: Executing an IfElseTask whose Syntax property is not WorkflowScriptSyntax.Liquid or WorkflowScriptSyntax.JavaScript — typically an unset/default enum value, an unrecognized syntax string deserialized from workflow JSON, or programmatic creation without assigning Syntax.

Common situations: Hand-edited or imported workflow definitions with stale syntax names after a version change; a newly added WorkflowScriptSyntax member that IfElseTask does not handle; missing Syntax assignment when instantiating the activity in code.

Related errors

AI-assisted analysis of OrchardCMS/OrchardCore@4306c0717f (2026-09-13). Data as JSON: /api/errors/61ee721d4215a46b. Report an issue: GitHub.

Appendix: source

Thrown at src/OrchardCore.Modules/OrchardCore.Workflows/Activities/IfElseTask.cs:58

        set => SetProperty(value);
    }

    public WorkflowScriptSyntax Syntax
    {
        get => GetProperty(() => WorkflowScriptSyntax.JavaScript);
        set => SetProperty(value);
    }

    public override IEnumerable<Outcome> GetPossibleOutcomes(WorkflowExecutionContext workflowContext, ActivityContext activityContext)
        => Outcome(S["True"], S["False"]);

    public override async Task<ActivityExecutionResult> ExecuteAsync(WorkflowExecutionContext workflowContext, ActivityContext activityContext)
    {
        var result = Syntax switch
        {
            WorkflowScriptSyntax.Liquid => await _expressionEvaluator.EvaluateAsync(LiquidCondition, workflowContext, null),
            WorkflowScriptSyntax.JavaScript => await _scriptEvaluator.EvaluateAsync(Condition, workflowContext),
            _ => throw new NotSupportedException($"The syntax {Syntax} isn't supported for IfElseTask.")
        };

        return Outcome(result ? "True" : "False");
    }
}

View on GitHub (pinned to 4306c0717f)