Designers Troubleshooting Guide

• Jul 30, 2026
• 4 minutes to read

This topic describes how to resolve problems that can occur when you open Model Editor or Visual Studio designers.

Main Approach

Perform the following steps if you have problems with a designer:

1. Close opened windows with the designers in Visual Studio.

2. Close Visual Studio.

3. Remove the contents of the bin and obj directories in each project and the .vs folder in the solution.

4. Run Visual Studio as an administrator.

5. Build your solution and ensure that the build succeeded.

Open the designer again. Refer to the following sections if it still throws an error.

Common Designers Issues

A designer throws the “Dictionary already contains class info“ error

Solution: Use project-to-project references instead of file assembly references for projects in an XAF solution. Microsoft recommends this to manage references in a project and our Model Editor requires project-to-project references to collect accurate dependency information.

You receive the “Package Load Failure“ error when you load a designer

Solution: Close Visual Studio and navigate to the folder where its executable (devenv.exe) is located:

• VS 2026: %ProgramFiles%\Microsoft Visual Studio\18\Professional\Common7\IDE\
• VS 2022: %ProgramFiles%\Microsoft Visual Studio\2022\Professional\Common7\IDE\

After that, execute the following command in the command prompt:

devenv /ResetSkipPkgs

It is also possible that extensions do not load because the Visual Studio component’s cache is corrupted. Clear the cache as described in the following articles:

• Clear Visual Studio Component Cache
• Clear MEF Component Cache

Model Editor Issues

Model changes are shown as a plain XML instead of in the designer

Solution #1: Try the previous solution.

Solution #2: Ensure the DevExpress.ExpressApp.Design.NetCorePackage extension is enabled. Click the Extensions | Manage extensions menu item. In the invoked window, click the Enable button (if the extension is disabled). Restart Visual Studio.

You can disable this extension when you received the following notification:

We recommend that you do not disable DevExpress extensions as this may cause functionality issues.

This extension can be disabled due to a corrupted installation. Refer to the articles below for more information.

• Extensions get automatically disabled when starting VS 2015
• Web Essentials disabled on VS 2015 start

Solution #3: Ensure that the “Subtype Designer” is added unnecessarily to xml-based files like csproj issue is fixed in the version of Visual Studio you use. Otherwise, update your IDE.

Your Model changes are contained in the XAFML file, but are not applied to an application or higher level modules

Solution:

1. Ensure that the Model.DesignedDiffs.xafml file’s Build Action is set to EmbeddedResource;

   

2. Ensure that your changes are not overridden in higher application model layers. For example, if you customized the Model in a platform-agnostic module (MySolution.Module/Model.DesignedDiffs.xafml), check the Model.xafml files of your platform-dependent module and project, respectively.

You have one of the following issues in a .NET project:

• The Model Editor frame was created, but showed errors inside.
• The Model Editor frame was not created.
• You received NotImplementedException.
• You received the “The operation could not be completed“ error.

Solution: Follow the steps below to collect diagnostic information and send it to DevExpress Support.

1. Close your Visual Studio, navigate to %USERPROFILE%\AppData\Roaming\eXpressAppFramework\, and archive the folder content.
2. If the Model Editor frame was not created or you received NotImplementedException or “The operation could not be completed” errors, collect the inner exception message and callstacks using another Visual Studio instance. The following article describes how to do this: How to obtain a design-time exception call stack.
3. Create a new Support Center ticket (https://supportcenter.devexpress.com/ticket/create) and attach the resulting diagnostic information as well as screenshots showing the exact steps to reproduce, the actual and expected results, your Visual Studio “About” information, and the CSPROJ of the projects you tested. Optionally, attach a small debuggable sample where this behavior can be reproduced in a stable manner.

Other Issues

You received any other errors

Solution: Debug Visual Studio where designers are opened as described in the following help topic: Get Exception Call Stack Of Design-Time Errors In Visual Studio.

You did not find an appropriate solution in this topic

Solution: Close Visual Studio and rerun the DevExpress Unified Component Installer in the Repair mode.

If designers still do not work, submit a support ticket and attach the Visual Studio Activity Log and DevExpress installation log.