Question

When I try to do that I get the error “Changed to 64-bit applications are not allowed”

Will this be fixed in Visual Studio 2010?

Answer 1

According to Somasegar, this was planned as part of VS2010, but it has not happened. In the comments to that post, people have complained that it is not supported in the Beta 1. There is a reply from Dustin Campbell (a program manager on the Visual Studio team) that says:

Adding true support for Edit and Continue to the 64-bit version of the CLR is a fairly large work item, and other features were prioritized higher due to the fact that there is a reasonable workaround in most cases (i.e. target x86). … We are absolutely committed to revisiting Edit & Continue in the next release to add 64-bit support and address other holes in that particular feature. However, changing the default to x86 isn’t just to support Edit & Continue. There are many other customer pain issues that switching to x86 will address.

This suggests to me that it is not likely to happen. Edit & Continue is supported on 64 bit machines, just not if the platform target is set to x64.

EDIT: From Visual Studio 2010 Beta 2’s help files:

Edit and Continue is not supported when debugging 64-bit code, the Compact Framework, optimized code, mixed native/managed code, or SQL CLR code. If you try to apply code changes in one of these scenarios, the debugger puts up a dialog box explaining that Edit and Continue is not supported.

Assuming the documentation is correct and up-to-date, this means it is not supported. This applies to C#, VB.Net and C++.