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The controller for ASPxUploadProgressHandlerPage.ashx was not found or does not implement IController
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A primary key field specified using the KeyFieldName property is not found
The 'Key expression is undefined' error occurs when you use GridViewExtension.BindToLINQ / GridViewExtension.BindToEF methods
The X has no access to path Y" or "Access to the path X is denied (Image and File Extensions)
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Data binding directly to a store query (DbSet, DbQuery, DbSqlQuery, DbRawSqlQuery) is not supported
An alert message with the HTML/JavaScript/CSS content appears when you use callback-aware extensions
An extension with 'X' name is already rendered
'System.Web.WebPages.Html.HtmlHelper' does not contain a definition for 'DevExpress'
The call is ambiguous between the following methods or properties
Cannot convert lambda expression to type X because it is not a delegate type
An error occurred while encrypting a control's callback state
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The call is ambiguous between the following methods or properties: 'DevExpress.Web.Mvc.UI.HtmlHelperExtension.DevExpress'

Error Description

This error usually occurs when you switch to an MVC 5 framework that references the DevExpress.Web.Mvc5 assembly. The DevExpress.Web.Mvc and DevExpress.Web.Mvc5 assemblies cannot be referenced at the same time within a single application.

Solution

Starting with v12.2.14 and v13.1.8, it is necessary to use the DevExpress.Web.Mvc5 reference instead of the DevExpress.Web.Mvc reference if the target ASP.NET MVC version is v5.

  • If you use MVC 5, remove the DevExpress.Web.Mvc reference from the *.proj and Web.config files, and exclude this assembly from deployment.
  • If you use MVC 4, remove the DevExpress.Web.Mvc5 reference from the *.proj and Web.config files, and exclude this assembly from deployment.

If it does not help or you are sure that you did not change the MVC framework version, follow the recommendations from the following topic: Type 'X' exists in both assemblies / Type 'X' is ambiguous in namespace 'Y'.

Dashboard Suite

The MVC Dashboard Suite has its own assemblies for MVC 5 applications and MVC applications of previous versions:

  • DevExpress.Dashboard.v15.2.Web.Mvc5 for MVC 5 applications.
  • DevExpress.Dashboard.v15.2.Web.Mvc for applications of previous versions.