Experience Manager Update preview raises "Cannot perform runtime binding on null reference"

Question

I am using the following code to site edit the component links(multi-allowed field).

@foreach(var comp in Fields.leader_list) {

    <tcdl:ComponentField name="Fields.leader_list" index="@comp.Index">
    ...
    </tcdl:ComponentField>

}

I am able to publish the page and the span tag in the source for the field is (seems to be correct) where leader_list is the field having the comp links:

<!-- Start Component Field: {"XPath" : "tcm:Content/custom:Content/custom:leader_list[1]"} -->

Now once I update the comp links and click "Update Preview", the components are getting updated in tridion but it's throwing the below error while publishing the component:

"Cannot perform runtime binding on null reference"

Please provide a direction.

Answer 1

I have experienced exactly the same problem and I figured that this error is caused by the Razor Mediator when trying to access an object which is null, for example, a component link field which does not contain a value. Yo might want to check your Razor Template Building Block for possible "null" values. Keep in mind that experience manager calls the templates for rendering.

In my case I was trying to access an "optional" field without checking whether it was empty or not, and when empty (Removed from Experience Manager), I got the infamous:

Cannot perform runtime binding on null reference

The steps I took to figure this out are: 1. Open the Page Template you are Using and run it against the page you are working on 2. Open each individual Component Templates the page renders and render them with the components you are using in such page.

This way you'll see what's the Template causing the issue, then, debug further (I use the @Debug("1") to write debug lines within the razor tbb).

Hope this helps.

Answer 2

This has started working now. Not sure what was the cause.