I am getting this error a lot:
Feature ‘{insert feature here}‘ cannot be used because it is not part of the
ISO-2 C# language specification
I am working on a .NET 3.5 website that I’ve worked on on and off for about two years. I’ve never seen this error before my most recent around of updates. I’m using a decent amount of LINQ coding throughout and I get these errors related to much of the LINQ code. Based on what I’ve read it seems like even though I’m using .NET 3.5, for some reason it thinks I’m using 2.0. But I can’t find anything that says how to fix it.
One example of a problem is that if I try to add a new item to the App_Code directory, I do not get the option to add a LINQ to SQL dbml file.
If anyone can shed some light on how exactly I would fix this, I would much appreciate it.
I was unable to locate an “Advanced” option under the build tab. I have a feeling it is probably because it is a web app. I looked through the web.config and found 2 parts that may be important. Most things referenced 3.5.0.0 or v3.5. The settings are consistent with older backups of the web.config from when there were no errors. By the way, only intellisense and things within VS2010 are giving me problems. The website is running error free.
I have completed a total uninstall and re-install of VS2010 and I’m still having the same issue. I fired up my old install of VS2008 and I am NOT having this issue there. However, I would MUCH prefer to use VS2010 on this project.
I opened the website in VS2010 on my work computer, and there are no errors reported. This is making me think that there is something on my laptop that is causing the problem. As I noted above, I completely reinstalled Visual Studio 2010 and I am still having the problem. What does this leave? I have only one extension installed in VS, and it’s the same one at work and on my laptop. Also, I did not reinstall the extension after reinstalling VS, and the problem persists.
Both PC’s run Win7 Ultimate. Have VS2008 and VS2010 installed. VS2010 has the same extension installed on both. On my laptop I have the full version of SQL Server 2008 installed, but only the Management Studio on my desktop (we have a server in the office). Would SS2008 have anything to do with it?
Jon Skeet’s answer is mostly correct. The location for the update is in the “Property Pages” which I got to by right-clicking on the name of the website, clicking Property Pages, the Build item, then target framework.
The extension I use, Solution Navigator, has it’s own heading for the solution. Right-clicking on it DOES NOT give me the Property Pages option. By chance I right clicked on the title of the website under the solution heading and was presented with the Property Pages option. In there was the Build tab which contained the target framework option.
Once I finally found the target framework option, it was indeed set to .NET 2.0 for some reason. I changed it to 3.5, reloaded the solution, and now it works great.
Thanks a million Jon for your help and time working with me!!