“SyntaxError: Unexpected token < in JSON at position 0”

Question

In a React app component which handles Facebook-like content feeds, I am running into an error:

Feed.js:94 undefined \"parsererror\" \"SyntaxError: Un

Answer 1

For me, this happened when one of the properties on the object I was returning as JSON threw an exception.

public Dictionary Clients { get; set; }
public int CRCount
{
    get
    {
        var count = 0;
        //throws when Clients is null
        foreach (var c in Clients) {
            count += c.Value;
        }
        return count;
    }
}

Adding a null check, fixed it for me:

public Dictionary Clients { get; set; }
public int CRCount
{
    get
    {
        var count = 0;
        if (Clients != null) {
            foreach (var c in Clients) {
                count += c.Value;
            }
        }
        return count;
    }
}