Description

When using Sitecore Forms, accessing a page with a form might fail with an unhandled exception if the URL of the page contains query string parameters without any value, for example:

?param=

An error similar to the following can be found in the log records:

Exception: System.ArgumentNullException
Message: Value cannot be null.
Parameter name: key
Source: mscorlib
   at System.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector, IEqualityComparer`1 comparer)
   at System.Linq.Enumerable.ToDictionary[TSource,TKey,TElement](IEnumerable`1 source, Func`2 keySelector, Func`2 elementSelector)
   at Sitecore.ExperienceForms.Mvc.Pipelines.RenderForm.SetFormParameters.Process(RenderFormEventArgs args)
   at (Object , Object )
   at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
   at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs](String pipelineName, TArgs args)
   at Sitecore.Mvc.Pipelines.PipelineService.RunPipeline[TArgs,TResult](String pipelineName, TArgs args, Func`2 resultGetter)
   at Sitecore.ExperienceForms.Mvc.Html.HtmlExtensions.BeginRenderRouteForm(HtmlHelper htmlHelper, FormViewModel model, Boolean isPost)
   at ASP._Page_Views_FormBuilder_Form_cshtml.Execute() in [your_path]\Views\FormBuilder\Form.cshtml:line 14
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy()
   at System.Web.Mvc.WebViewPage.ExecutePageHierarchy()
   at System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage)
   at System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)

Solution

To resolve the issue, consider one of the following options:

• Upgrade the Sitecore XP instance to Sitecore XP 9.3.0 or later.
• For Sitecore XP 9.0.2 download and install the patch compatible with the affected product version found on this page: https://github.com/sitecoresupport/Sitecore.Support.324457/releases