Hi Matt,

So on my product page/view I'm rendering this partial:

Html.Partial("/Views/Partials/MediaLayers/_CoursePricingLayer.cshtml");

This is the stack trace when I rendering a the product page:

[ModelBindingException: Cannot bind source content type Umbraco.Web.PublishedModels.Course to model type ICSLearnV8.core.Models.ProductPage. The source is a ModelsBuilder type, but the view model is not. The application is in an unstable state and should be restarted.]
   Umbraco.Web.Mvc.ContentModelBinder.ThrowModelBindingException(Boolean sourceContent, Boolean modelContent, Type sourceType, Type modelType) in D:\a\1\s\src\Umbraco.Web\Mvc\ContentModelBinder.cs:159
   Umbraco.Web.Mvc.ContentModelBinder.BindModel(Object source, Type modelType) in D:\a\1\s\src\Umbraco.Web\Mvc\ContentModelBinder.cs:94
   Umbraco.Web.Mvc.UmbracoViewPage`1.SetViewData(ViewDataDictionary viewData) in D:\a\1\s\src\Umbraco.Web\Mvc\UmbracoViewPageOfTModel.cs:152
   System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +99
   System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +107
   Umbraco.Web.Mvc.ProfilingView.Render(ViewContext viewContext, TextWriter writer) in D:\a\1\s\src\Umbraco.Web\Mvc\ProfilingView.cs:25
   System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection) +277
   System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData) +91
   System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName) +32
   ASP._Page_Views_Course_cshtml.Execute() in C:\Users\stuartp\source\Workspaces\ICSLearnV8_Vendr_Test\ICSLearnV8_Vendr_Test\ICSLearnV8_Vendr_Test\Views\Course.cshtml:34
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +198
   System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +105
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +78
   System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +256
   System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +107
   Umbraco.Web.Mvc.ProfilingView.Render(ViewContext viewContext, TextWriter writer) in D:\a\1\s\src\Umbraco.Web\Mvc\ProfilingView.cs:25
   System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +290
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +56
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +52
   System.Web.Mvc.Async.<>c__DisplayClass3_6.<BeginInvokeAction>b__4() +198
   System.Web.Mvc.Async.<>c__DisplayClass3_1.<BeginInvokeAction>b__1(IAsyncResult asyncResult) +100
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
   System.Web.Mvc.<>c.<BeginExecuteCore>b__152_1(IAsyncResult asyncResult, ExecuteCoreState innerState) +11
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +45
   System.Web.Mvc.<>c.<BeginExecute>b__151_2(IAsyncResult asyncResult, Controller controller) +13
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
   System.Web.Mvc.<>c.<BeginProcessRequest>b__20_1(IAsyncResult asyncResult, ProcessRequestState innerState) +28
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +576
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +132
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +163

Here's the top of the product page view -

@inherits Umbraco.Web.Mvc.UmbracoViewPage<object>
@using ICSLearnV8.core;
@using Vendr.Core.Models;
@using ICSLearnV8.core.Models;
@using Umbraco.Core.Models.PublishedContent;
@using System.Web.Mvc.Html;
@using Umbraco.Web;
@using ICSLearnV8.Models;
@using ICSLearnV8.Helpers;
@using ICSLearnV8.Controllers.SurfaceControllers;
@{
    Layout = "_Layout.cshtml";
    IPublishedContent CurrentPage = UmbracoContext.PublishedRequest.PublishedContent;
    var homePage = CurrentPage.AncestorOrSelf("home");
    var siteSetting = homePage.DescendantsOrSelfOfType("siteSettings").First();
    var courseController = new CourseActionsController();
    var facStyle = CurrentPage.Value("facultyStyle");
    var heroItems = CurrentPage.Value<IEnumerable<IPublishedElement>>("heroItems");

}

@Html.Partial("~\\Views\\Partials\\_RenderHeroItems.cshtml")

@{
    <section class="course-wrap">
        <div class="container">
            <div class="row">
                <div class="col-lg-8 padding-bottom course-copy">
                    @{
                        if (CurrentPage.Value<bool>("displayAnchor"))
                        {
                            @Html.Partial("~\\Views\\Partials\\MediaLayers\\_AnchorLayer.cshtml")
                        }
                        Html.Partial("/Views/Partials/MediaLayers/_CoursePricingLayer.cshtml");

Here's the beginning of the _CoursePricingLayer.cshtml -

@inherits Umbraco.Web.Mvc.UmbracoViewPage<ProductPage>
@using ICSLearnV8.core;
@using Vendr.Core.Models;
@using ICSLearnV8.core.Models;
@using ICSLearnV8.Helpers;
@using ICSLearnV8.Controllers.SurfaceControllers;
@using Umbraco.Core.Models.PublishedContent;
@using Umbraco.Web;
@using NPoco.fastJSON;

@{
    IPublishedContent CurrentPage = UmbracoContext.PublishedRequest.PublishedContent;
    var store = Model.Value<StoreReadOnly>("store", fallback: Fallback.ToAncestors);
    var addedProductReference = TempData["addedProductReference"]?.ToString();
    var renderForm = false;
    var homePage = CurrentPage.AncestorOrSelf("home");
    var siteSetting = homePage.DescendantsOrSelfOfType("siteSettings").First();
    var courseController = new CourseActionsController();
    var mediaLayer = Model;
    var facStyle = CurrentPage.Value("facultyStyle");
    var layerTitle = !string.IsNullOrEmpty(mediaLayer.Value<string>("layerTitle")) ? mediaLayer.Value<string>("layerTitle") : mediaLayer.Name;
    var courseCode = CurrentPage.Value<string>("courseCode");

    var isAmp = false;
    if (Request.RawUrl.Contains("amp=1"))
    { isAmp = true; }

    <section id="@(layerTitle.ToLower().Replace(" ", "-"))" class="section spacer-30">
        <div class="row bg-white">
            <div class="col-lg-6 col-md-6 m-auto">
                <div class="ics-popover d-flex">
                    <div class="col-12 d-flex justify-content-center align-items-center">
                        <img src="/media/738552/price-tag-large.png" alt="price tag icon" loading="lazy">
                        <h2 class="@facStyle-prim-font mb-0 course-price">£121/month <span class="block">interest-free</span></h2>
                    </div>
                    <div id="popover-content" style="display:none">
                        This is an estimate based on the current exchange rate.<br>
                        Course fees will be charged in GBP.<br><br>
                        <div class="row">
                            <div class="col-4">
                                <strong>Monthly:</strong><br>£121/month
                            </div>
                            <div class="col-4">
                                <strong>Deposit:</strong><br>£129
                            </div>
                            <div class="col-4">
                                @Html.Hidden("productReference", Model.GetProductReference())
                                <p><strong>Total Price</strong><br><span>£@(Model.CalculatePrice())</span></p>
                            </div>

To confirm the site is running Umbraco V8.18 with Vendr v 2.21 installed...

Thanks, Stuart