Error building C# Solution using xbuild (mono)

Question

I've searched the depths of the internet and I cannot find an answer or workaround for this problem. I have no idea either what is causing it.

I keep getting the error in Xamarin Studio:

Error: Error building target GetReferenceAssemblyPaths: UNC paths should be of the form     \\server\share.

Can someone explain this to me?

Here's a link to one of the project files: http://pastebin.com/qZ5uGL9S

Answer 1

If you inspect your project file you have a couple of extra backslashes in some of your FXCopy rule paths i.e.

<CodeAnalysisRuleSetDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools**\\**Rule Sets</CodeAnalysisRuleSetDirectories>
<CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop**\\**Rules</CodeAnalysisRuleDirectories>
<CodeAnalysisRuleSetDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools**\\**Rule Sets</CodeAnalysisRuleSetDirectories>
<CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop**\\**Rules</CodeAnalysisRuleDirectories>

The compiler is probably picking these up as UNC paths, replace them with a single backslash and it should compile ok.

Answer 2

Slightly unrelated, but I received a similar error immediately when building a coworker's old Visual Studio project:

Error: Failed to write to log file "\\projName.log". The UNC path should be of the form \\server\share.

I fixed it by changing the Project Configuration Properties Build Log File field. It had incorrect variables that were evaluating to blank:

$(IntDir)\$(MSBuildProjectName).log

Fixing this allowed the build to run flawlessly. Maybe this will help someone, or I can open a new question and answer it.

Answer 3

I UnChecked the use MSBuild and this fixed it.

Answer 4

When I created my project in Microsoft Visual Studio 2012, I selected TargetFrameworkVersion 3.5. Visual Studio 2012 creates project files with ToolsVersion="4.0". Apparently the Mono installation (mine was 3.2.3) doesn't digest the 4.0 toolset very well. So I opened my csproj file in Notepad and changed it to ToolsVersion="3.5". It fixed the problem.

NB: TargetFrameworkVersion and ToolsVersion are two different things. ToolsVersion specifies the version of MSBuild tools to use when building your project whereas TargetFrameworkVersion is the version of .NET Framework to target.