|Websites ... so many problems unless you understand what is going on ...
There are two major components to a website: the Front end and the Back end.
The Back end is written in C# (or VB, or PHP) and executes on the Server computer within the web server software.
And that means that when you call MessageBox you are executing code on the Server, not the Client - and even if MessageBox is installed on eth Server, the message would display there, not on the Client browser.
It appears to work in development because the Server and Client are both running on the same machine - the server MessageBox pops up and it looks fine because nothing indicates where it's from.
In production, they aren't the same computer, and the MessageBox (if any) will pop up on the Server (which probably doesn't have a display, and even if it did nobody is looking at it) so the Client just appears to freeze and the page times out without responding.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
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