asp.net: Invalid postback or callback argument error

 <%@ Page EnableEventValidation="false" %>

change true to false

reference:- https://stackoverflow.com/questions/7476329/asp-net-invalid-postback-or-callback-argument

How to print date before last five years from today in sql server

 select  DATEADD(YEAR, -5, GETDATE())

What is inproc in web.config in session tag

 https://www.c-sharpcorner.com/UploadFile/3d39b4/inproc-session-state-mode-in-Asp-Net/

How to change port of website in visual studio

>Open visual studio

> Right click on project and go to property pages or property window

or go to debug menu at the top

click on debug properties.

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https://www.aspsnippets.com/questions/199412/Solved-Change-Port-Number-of-IIS-Express-in-Visual-Studio/

https://stackoverflow.com/questions/44506216/how-do-i-change-the-debug-port-in-visual-studio-2017

https://blog.novacare.no/how-to-change-portnumber-for-sql-express-development/#:~:text=In%20Solution%20Explorer%2C%20right%2Dclick,in%20the%20Project%20URL%20box.

 https://stackoverflow.com/questions/33742241/how-to-change-website-url-in-visual-studio-2015

Convert to application in website in webapp in IIS server -asp.net and how to revert it back to webapp

 >Open IIS

> Just right click on the folder that is webapp

> Click on convert to webapp

> To revert it back just click on delete, it will be converted into folder