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When I attempt to change the startup form in a VB.NET project, I receive the following error.
After the error pops up, the forms no longer appear in the list and the project will not run.
I am running Microsoft Visual Studio Professional 2022 (64-bit) - Current
Version 17.2.0
If I open the same project in Visual Studio 2013, I am able to see the Form in the startup objects and select it without any error. I also use the same install of Visual Studio 2022 to work with existing projects but haven't tried to change the startup form because I do not wish to break the project.
Is this a bug in Visual Studio?
Thanks
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Yes it is a defect.
You can work around it by unloading the project and editing "/My Project/Application.myapp". Change the value of <MainForm> to the correct form name.
It seems as though VS misses updating this value when the startup form is changed. After that point Anytime the Project Properties are change, VS overwrites the startup form in other places (Application.Designer.vb in my case) with the value from this file.
Fixing the name in Application.myapp has permanently remedied the issue for me.
HI @Rich Clark
I tried the solution but it did not work for me.
Then the error is thrown in the Project Properties form it seems to make multiple changes to the "/My Project/Application.myapp" file as follows:
The <MainForm> setting is no longer present in the file.
The <ApplicationType>0</ApplicationType> setting is missing from the file.
The <MySubMain> setting is set to true instead of false.
I readded the missing values and changed the <MySubMain> setting back to false but the project still fails to run giving the error:
Severity Code Description Project File Line Suppression State
Error BC30420 'Sub Main' was not found in 'MyApplication'. WindowsApp1 C:\Users\Phill\Source\repos\WindowsApp1\WindowsApp1\vbc 1 Active
I tried adjusting the settings further but was not able to fix the issue without loading the application in the 2013 version of Visual Studio.
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I couldn't change the startup form as only a single form appears in the property tab. Going into Solution Explorer opening Application Events, My Application and clicking on 'OnCreateMainForm()' opens the code window where I changed the form name directly via Me.Mainform = Global.projectname.nameofmycurrentform (Leaving off the .vb extension). Intellisense will show the options for selection. I was able to run the new form and change form names at will. Hope this helps someone else.
Hi Allan,
The problem is, once the error message has triggered inside the project properties, the OnCreateMainForm() method is no longer available inside the Application Events. The error occurs when you click the dropdown box of the Startup Objects in the Project Properties and then click on/reselect form1. It looks like it's supposed to be fixed in the update V 17.3
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Hello Phill,
Is update 17.3 coming soon? I've got this problem with 17.2.6 and it says I'm up to date.
It seems that it is a defect:
By the way, there is a new update for Visual Studio.
I installed the update but the problem still exists. Thanks for sharing the other posts.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(313.6, 6%, 40%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EI%3C/text%3E%3C/svg%3E)
Close the project, then
2.Edit ..xxx.vbproject to change
<MyType>WindowsFormsWithCustomSubMain</MyType> to <MyType>WindowsForms</MyType>
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I try in this way, but it do not works.
I edit Application.myApp, change MainForm from Form1 to Form2. In the Project panel, it appears Startup Form as Form2. But when I run the project, it is still start up with Form1 .
Hi, I made a complaint to Visual Studio as no upgrade should have such a major impact on functionality and productivity. It was I believe an earlier upgrade which caused the problem as I had no trouble when first using it. I received a response with a link which enabled me to download a preview version of the next major update. This version works fine. You may want to report it as a new issue to obtain the link.
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(300.8, 42%, 39%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EWS%3C/text%3E%3C/svg%3E)
It's hard to believe that Microsoft has made such a big bug on VS