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New installation - designer error - crash #4959
Description
George Anifantakis asked 2026-04-11 08:59:48 UTC
Hi,
I have created an installation of 4.0.11 version in vs 2022 and every time i open the designer i am geting the error below.
Unable to cast object of type 'Wisej.Web.Page' to type 'Wisej.Core.IWisejControl'.
This is happening in a new created project from web application template. Compilation is working fine but the designer crashes with the above error.
The new created project is using framework 4.8.1 and .net 9, the defaults and wisej version 4.0.11.
I have tried..
Uninstall both versions of wisej reboot and reinstalling** only 4.0.11**
Compile the project, close VS and reopen it.
Unsinstall and resinrall the product 4.0.11 several times.
Delete the folder AppData\Local\Microsoft*VisualStudio\17.0_xxx* and recreated fron vs
Nothing works..!!
I had version 3.5 installed if this helps.
Thnaks
George
Activity
itg-assistant commentedon Jun 17, 2026
George Anifantakis answered 2026-04-11 13:54:39 UTC
Following the installer video i found that Wisej.NET-3-VS2022.vsix seeds to be installed first. I did that following the instruction then install ver 4.0.11. Now the templates have only Wisej 3 templates while Wisej 4 templates are missing. In the extentions installed tab both Wisej 3 and wisej 4 environments are installed and active.
itg-assistant commentedon Jun 17, 2026
George Anifantakis answered 2026-04-11 13:56:47 UTC
Does anybody know how to completed reset VS wisej environment properly to do the installation procedure agian ?
itg-assistant commentedon Jun 17, 2026
Frank (ITG) answered 2026-04-11 19:49:43 UTC
Hi George, the best way to uninstall an extensions is to go to Extensions – Mange Extensions, select extension and uninstall. Restart VS. Can you please post a screenshot of the Wisej.NET extensions after you did a fresh install? Best regards, Frank
itg-assistant commentedon Jun 17, 2026
George Anifantakis answered 2026-04-15 09:25:38 UTC
Hi Frank, thanks a lot for your response.
I have procceded with the below acrions.
Uninstall from the VS extenions all Wisej products.
Restart the pc.
Fresh install using https://www.youtube.com/watch?v=8BTvHicJesc instructions.
After installtion finished, i have created a new wisej web aplication. When i open the designer same error occured.
Sending also screenshoots.
Thanks
GA
itg-assistant commentedon Jun 17, 2026
George Anifantakis answered 2026-04-15 09:32:06 UTC
And a screenshot of the nugget package. It has other version.
itg-assistant commentedon Jun 17, 2026
JD answered 2026-04-15 09:42:06 UTC
It's not a crash. It's an exception that a class cannot be cast to an interface. It means VS loaded multiple versions of the same assembly, which means you have multiple versions of Wisej.NET in the same project or an installation that is wrong. Delete all .bin and all .obj, uninstall all installations of wisej, search for any Wisej.Core and Wisej.Framework dlls and make sure the machine is clean. Install Wisej 4 extension and it will work.
Otherwise try on a clean machine.
itg-assistant commentedon Jun 17, 2026
Paul answered 2026-04-16 18:05:51 UTC
Hi George,
I installed Wisej in Visual Studio 2022 in the following order:
Wisej 3
Wisej 4
I then created a new project using Wisej 3 targeting .NET 9, and it opened correctly in the designer.
I’ve attached my test project in case it helps with troubleshooting.
Regards
itg-assistant commentedon Jun 17, 2026
George Anifantakis answered 2026-04-17 07:54:08 UTC
Hi,
After uninstall from extentions as wisej products, I did a deep search deleting all wisej dlls that i found in several folders.
After that, i install only ver 4.0.11 and it seems to worl ok. I think that the problem occured from old dlls that are not deleted after uninstall from all folders.
Thanks a lot for your support.
GA