Q:

TFS - Errors: "The type or namespace name 'blabla' does not exist in the namespace 'blublu' (are you missing an assembly reference?)

I have an issue, unfortunately I didn't find a solution which can fix my problem, other solutions can be found, but no one works for me.
When I build locally my solution, all is perfect, but when I launch the Build Definition with this solution I have some issues.
Firstly severals erros such as:
 Console.cs (5): The type or namespace name 'Core' does not exist in the namespace 'Toto' (are you missing an assembly reference?)
 Enti\Extensions.cs (602): The type or namespace name 'Attribute' could not be found (are you missing a using directive or an assembly reference?)

and other with the same error as the last one.
To help me I have these Warnings as well, hereunder, one of them (others are similar):
C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Microsoft.Common.targets (1605): Could not resolve this reference. Could not locate the assembly "Comarch.B2.Core". Check to make sure the assembly exists on disk. If this reference is required by your code, you may get compilation errors.

What I tried:

The references such as "Core" for instance are well put in the
project References; 
Removed and added warning references 
Checked the version Framework dotNET The path lenghts
(http://www.gitshah.com/2011/06/visual-studio-2010-fixing-referenced.html)

For instance the first error above:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using .Core.Interfaces.Dictionaries;

namespace Toto.Presentation.Extensions.Interfaces
{
    public class Console
    {
        ...
    }
}

Then a scrap of my LOG:
>  C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Microsoft.Common.targets(1605,5):
> warning MSB3245: Could not resolve this reference. Could not locate
> the assembly "Common". Check to make sure the assembly exists on disk.
> If this reference is required by your code, you may get compilation
> errors.
> [c:\bw\41\src\F\TFS\te\Pro\Extensions\Toto.Presentation.Extensions.Interfaces\Toto.Presentation.Extensions.Interfaces.csproj]
>              For SearchPath "{HintPathFromItem}".
>              Considered "..\..\..\..\..\..\..\..\..\..\Toto.Common.dll", but it didn't exist.
>              For SearchPath "{TargetFrameworkDirectory}".
>              Considered "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\Toto.Common.winmd",
> but it didn't exist.
>              Considered "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\Toto.Common.dll",
> but it didn't exist.
>              Considered "C:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.0\Toto.Common.exe",
> but it didn't exist.

Thank you very much for helping me, I stuggled for 2 days ago.

A:

To solve this error, you need to make sure that this assembly will exist in the correct path on your build agent. 
In the .csproj file of your project, it defines which items you refer to and where it locates. 
<Reference Include="xxx">
      <HintPath>..\..\xxx\xxx.dll</HintPath>
</Reference>

And in your project, the HintPath seems to be "..\..\..\..\..\..\..\..\..\..\Toto.Common.dll". You could check on your build agent server, does this dll be downloaded. If not, please check the Repository Mappings of your build definition.
The "..\" means return to the up level. It has 10 "..\", so need to return to 10 levels up from where the .csproj files locates. 
I suggest that you reposition your Toto.Common.dll. You could put your project/solution and the referenced dll in a one folder and refer to use again in your project. Then in the Repository mappings, map this folder. Another condition is that you want to get this dll after another project builds. You need to map both the 2 projects and build both of them in your definition.

