Visual Studio 2010 beta broke my websites

After all the hype about the release of Visual Studio 2010 Beta I thought I’d give it a go and see for myself, so I downloaded a copy and installed it. This was ‘quick’ and painless, I say quick but I’m fortunate at work to be on a T1, so it only took a few minutes to download the Professional Beta 1 ISO (1.1GB). I mounted the the image and ran the setup, this wanted a reboot part and continued installing once I’d logged back in. When it was done I was given the same prompt as after installing any previous versions – check for updates, which I did.

Unfortunately before I could fire things up I was asked to have a look at a website that was misbehaving, so fired up my local copy and BAM nice YSOD. Part of the installation had changed all my Application Pools to use ASP.NET v4 rather than good old v2 and this was causing my YSOD. Nice! All I needed to do was select v2 on the App Pool for the project I needed to look at and everything was back to normal. However this isn’t a great experience for me, you’d think someone would have tested this behaviour and at least made a prominent warning about it. I highlight prominent because if there was a warning I didn’t see it!