SSJS redirect error 500

Question

I'm using a simple SSJS code to redirect according to an API call results. But I keep getting error 500.

Problematic code:

if(ContactId == 'null'){
    var errorURL = 'https://errorURL.com'
    Redirect(errorURL,false);
}

When I remove the Redirect(errorURL,false); there is no error.

I even tried to copy this one from the MC example document:

Redirect("http://example.com/index.html",false);

And I still get an error.

Full code:

<script runat="server">
    Platform.Load("core", "1.1.1");

    var RowCountFlag = Platform.Variable.GetValue("@RowCountFlag");

    if (RowCountFlag == 0) {

        var firstName = Platform.Variable.GetValue("@firstName");
        var lastName = Platform.Variable.GetValue("@lastName");
        var email = Platform.Variable.GetValue("@email");

        try {
           var url = 'https://test33333?timeout=60';
            var contentType = 'application/json';
            var headerNames = ["Username", "Token"];
            var headerValues = ["YYYYYYYYYYYYY", "XXXXXXXXXXXXxx"];

            var payloadObj = {
            "parameters":
                [
                    {"Key": "Acc_firstName",   "Value": firstName},
                    {"Key": "Acc_lastName",  "Value": lastName},
                    {"Key": "emal",    "Value": email},          
                ]
            }

            var OptInDE = DataExtension.Init("my de");
            var errorURL = 'www.erorURL.com'
            var payloadString = Platform.Function.Stringify(payloadObj);
            var result = HTTP.Post(url, contentType, payloadString, headerNames, headerValues);
            if (result.StatusCode == 200) {
                Variable.SetValue("@APIflag", '200')
                var responseStr = Stringify(result.Response[0])
                var cleanResponseStr = responseStr.replace(/[^\w\s]/gi, '')
                var starts = 9 + cleanResponseStr.lastIndexOf("ContactId")
                var ends = cleanResponseStr.indexOf("AssetId")
                var ContactId = cleanResponseStr.slice(starts,ends)
                Variable.SetValue("@ContactId", ContactId)
                var rows = Platform.Function.InsertDE("my de",["Serial Number","Resquest","Respond", "ContactId"],[SN,Stringify(payloadObj),Stringify(result),ContactId]);

                if(ContactId == 'null'){
                    var errorURL = 'https://errorURL.com'
                    Redirect(errorURL,false);
                }
            } else {
                var rows = Platform.Function.InsertDE("my de",["Serial Number","Resquest","Respond"],[SN,Stringify(payloadObj),Stringify(result)]);
                Redirect(errorURL, false);
            }
        } catch (e) {
            var rows = Platform.Function.InsertDE("Name_Your_Dolphin_IConduct_Log",["Serial Number","Resquest","Respond"],[SN,Stringify(payloadObj),Stringify(result)]);
            Write(Stringify("Err at API call: "+e));
            Redirect(errorURL, false);
        }
    } 

</script>

Answer 1

You forgot to set a semicolon in the line, where you define errorURL:

if(ContactId == 'null'){
    var errorURL = 'https://errorURL.com';
    Redirect(errorURL,false);
}

Also, I will suggest to do this test in a slightly better way, to ensure it actually does what you expect. In this case, it actually checks if your contact ID has the string value of 'null'. I expect this is what you need instead:

if(ContactId == null || ContactId == ''){
    var errorURL = 'https://errorURL.com';
    Redirect(errorURL,false);
}

Another reason for the error (which is more plausible in your case) is printing any output before the Redirect function. As the redirect function alters the header of the Cloud Page (responding with code 302 and the destination URL set in the Location header), outputting anything prior to the Redirect function results in an error, as the headers are set on the first line of code with output in it (e.g. utilising Write function).

So remove any usage of Write in your SSJS which might interfere with your Redirect, and also ensure no output is generated above the opening <script> tag.