I've located what's causing this, but I haven't been able to determine how to check whether the mediaSource.GetCropUrl is null or not. This is the source of the error:

if (!string.IsNullOrEmpty(product.GetPropertyValue<string>("MainProductImage")))
                {
                    //var media = ObjectFactory.Instance.Resolve<IImageService>().GetImage(product.ThumbnailImageMediaId).Url;
                    var media = product.GetPropertyValue<string>("MainProductImage");
                    var mediaSource = umbracoHelper.TypedMedia(media);
                    <a href="@url">
                        @*<img src="@mediaSource.GetCropUrl("umbracoFile", "store-product-medium")" class="main-image" />*@
                    </a>
                }
                else
                {
                    <a href="@url">
                        <img class="main-image" src="~/umbraco/ucommerce/images/ui/image_not_found.jpg">
                    </a>
                }

Specifically, the issue is caused here:

<img src="@mediaSource.GetCropUrl("umbracoFile", "store-product-medium")" class="main-image" />

...which is commented out above, since it's not working. I've tried to trap for the null reference like this, but it's not working either:

if (!string.IsNullOrEmpty(mediaSource.GetCropUrl("umbracoFile", "store-product-medium")))

Hi Jerritte,

Try something like

@(mediaSource?.GetCropUrl("umbracoFile", "store-product-medium") ?? "/umbraco/ucommerce/images/ui/image_not_found.jpg")

You'll need C#6. I think Umbraco also has an IfNullOrWhitespace() Extension method.

Stephano,

That's using C# 6, so I can't use that yet.

I found upgrading is usually fast and straightforward, however here is the pre C#6 way:

@(mediaSource != null ? mediaSource .GetCropUrl("umbracoFile", "store-product-medium") : "/umbraco/ucommerce/images/ui/image_not_found.jpg")

Stephano,

Ah...that works, and is clearly more concise! I should have known that. :)

Thanks!

I'm having the same issue. So this seems to be a BUG with NuCache. After a certain period my V8.0.1 website throws exactly this error.

A workaround makes no sense, because the value and mediaitem does exists. Somehow the cache gets invalid.

When i RELOAD NuCache from the Backend, the error is gone and the mediaItem "exists". I have to reload the cache several times a day.

Are there any special settings regarding nucache we have to take care of during the server setup? The AppPool\name has sufficient rights on the folders.

Thx in advance, Andreas

I've been getting this same problem with a new 8.0.1 install - it seems to happen after any AppPool restarts.

1. View page, get the error: Value cannot be null. Parameter name: mediaItem
2. Reload the in-memory / local file cache from the backend
3. View page - works
4. Recycle app pool
5. View page, get the error: Value cannot be null. Parameter name: mediaItem

Rinse and repeat. I'm keen on finding a better solution to this, as well.

Confirmed that this is resolved in 8.0.2 (at least, after recycling as listed above).

Instead of

ImageUrl = item.HasValue("image") 

We use

ImageUrl = item.Value("image") != null

And all is good! Umbraco 8.6

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