首先进行构建，然后尝试打开表单.

可能是表单正在使用未安装的组件，或者您没有该组件的设计时许可证.

Do a build first then try to open the form.

It could be that the form is using a component that is not installed, or you do not have a design time license for it.

清理解决方案，检查.aspx.cs名称和.aspx页面具有相同的名称?再次尝试并检查它是否工作正常.如果不工作，

***采用另一种形式，只需复制设计并粘贴为新形式，即可.

clean the solution, check whether .aspx.cs name and .aspx page have same name ? buid again and check whether it works fine .if not working then,

it is better to take another form ,simply copy the design and paste in new form ,

注意:不清楚是在WinForms，ASP.NET还是...中工作? br/>
在大多数情况下，我在WinForms中遇到此问题时，Designer.cs文件中存在一些损坏.

如果您具有可以打开的旧文件，而这是WinForms，建议您在无法打开的新窗体和旧窗体之间进行Designer.cs文件的比较.

寻找任何差异.

***，比尔

Note: not clear if you are working in WinForms, ASP.NET, or ... ?

Most of the time I''ve had this problem, in WinForms, there was some corruption in the Designer.cs file.

If you have the older file you can open, and this is WinForms, suggest you do a comparison of the Designer.cs files between the new Form you can''t open and the old Form.

Look for any differences.

best, Bill