Visual Studio 2010 Designer Error on Run

问题:

I am using using VS2010 and if I have a form open in designer mode and run my application the designer tab will no longer show the form designer but instead an error will be displayed (and it is only fixed by restarting the IDE) saying:

"To prevent possible data loss before loading the designer, the following errors must be resolved:"

1 Error:

"The designer could not be shown for this file because none of the classes within it can be designed. The designer inspected the following classes in the file: ##### --- The base class ##### could not be loaded. Ensure the assembly has been referenced and that all projects have been built"

I then shows the following call stack:

at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.EnsureDocument(IDesignerSerializationManager manager)
at System.ComponentModel.Design.Serialization.CodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager manager)
at Microsoft.VisualStudio.Design.Serialization.CodeDom.VSCodeDomDesignerLoader.PerformLoad(IDesignerSerializationManager serializationManager)
at System.ComponentModel.Design.Serialization.BasicDesignerLoader.BeginLoad(IDesignerLoaderHost host)

Any help is greatly appreciated this is really annoying.

Thanks,

Joel.

回答1:

I get this visual studio bug too now and then, and I deeply ignore the error text, instead I do the following:

1. Close the Design-tab
2. Reopens the Design mode by double click in Solution Explorer, or by right clicking Source code tab and select View Designer
3. Suddenly everything works again!

If not helping, you may have to change bullet 2 into: Close and restart Visual Studio.

Maybe this can help you out.

回答2:

I usually close the visual form, rebuild the solution, right-click then select "view designer" in the form code.

Very, very annoying. I am thinking of dropping back to VS2008.

回答3:

Close the form. Clean the solution. Rebuild the solution. Reopen the form. Worked for me when nothing else would.

回答4:

I had this same issue and I was able to resolve this by creating new project and then compiled and run the project and then I imported all the files and ran the project again and automatically it was working again did nothing extra.

回答5:

I'm able to avoid restarting VS by doing the following

1. Add a new user control
2. Drag and drop some of your custom user controls on to it (If it gives you an error, build the solution again).
3. Reopen your control.

In my case, I have a winforms project with several custom controls that are used by other custom controls. Whenever I open some of those custom controls, I get a the "The base class ..." error. Adding a new custom control, building the project and then adding some custom controls from my project to the new custom control allowed me to open the custom controls that were giving me the "The base class ..." error.

UPDATE: I think I found the problem. My controls were not 'added' properly to the csproj file. In the csproj file, the files for partial classes of UI controls/components need the 'DependentUpon' attribute.

E.x.: before:

<Compile Include="Windows\Forms\DataGridView.cs">
    <SubType>Component</SubType>
</Compile>
<Compile Include="Windows\Forms\DataGridView.Designer.cs" />

after:

<Compile Include="Windows\Forms\DataGridView.cs">
    <SubType>Component</SubType>
</Compile>
<Compile Include="Windows\Forms\DataGridView.Designer.cs">
    <DependentUpon>DataGridView.cs</DependentUpon>
</Compile>

回答6:

I had a situation where a custom user control appeared to be creating the error (not sure why) so I removed references to the user control from the form and the error went away.

回答7:

It seems that after installing SP1 the problem has gone away.

Thanks for your help everyone.

回答8:

I had the same problem using A control With Generics

      MvpUserControl<Presenter,IViewMode> : UserControl

what I do it's Remove the Reference and Add again, Clean and Rebuild the Solution I Hope this can be useful for anybody else

回答9:

I had the same problem with VS2010 SP1. Finally using Windows Update I saw some updates for Visual Studio and .Net, I installed them and is not happening any more.

回答10:

Old post, but for those whom may find this...

Just ran in to this error and for me it was relatively simple fix.

Found that it may have something to do with the names of your classes, and renaming the problematic class to a higher order. That is the alphabetical order it appears in the assembly (Where A is higher than Z).

MSDN Article

Good luck.

回答11:

This error occur if the Form class is not a first class in the file, for example if there is some helper class at the beginning of the file.

To solve this issue, move all other classes except Form class to the bottom of the file.

回答12:

Don't code in Form1.Designer.cs. Move your logic to Form1.cs (hit F7 on Form1.cs [Design] tab).

回答13:

"In the project file (.vcxproj), locate the entry for the target Framework version. For example, if your project is designed to use the .NET Framework 4.5, locate v4.5 in the element of the element. "

(Microsoft)

In my case the "v4.5" didn't exist so I add it, and everything is good now.

回答14:

I tried clean solution and re-build solution and worked for me. Hope this help!

回答15:

This solution works fine, please follow these steps below to solve your problem:

1. Check the reference if load correctly
2. Clean the solution and rebuild again
3. Clean the project and rebuild again
4. Clean your project and open it again