This documentation is archived and is not being maintained.

Compiler Error CS1726 

Error Message

Friend assembly reference 'reference' is invalid. Strong-name signed assemblies must specify a public key in their InternalsVisibleTo declarations.

A strong name signed assembly can only grant friend assembly access, made with the InternalsVisibleToAttribute, to other strongly signed assemblies.

To resolve CS1726, either sign (give a strong name to) the assembly to which you want to grant friend access, or don't grant friend access.

For more information, see Friend Assemblies (C# Programming Guide).


The following sample generates CS1726.

// CS1726.cs
// compile with: /keyfile:CS1726.key /target:library
using System.Runtime.CompilerServices;
[assembly:InternalsVisibleTo("UnsignedAssembly")]   // CS1726
// try the following line instead
// [assembly:InternalsVisibleTo("SignedAssembly, PublicKey=0024000004800000940000000602000000240000525341310004000001000100031d7b6f3abc16c7de526fd67ec2926fe68ed2f9901afbc5f1b6b428bf6cd9086021a0b38b76bc340dc6ab27b65e4a593fa0e60689ac98dd71a12248ca025751d135df7b98c5f9d09172f7b62dabdd302b2a1ae688731ff3fc7a6ab9e8cf39fb73c60667e1b071ef7da5838dc009ae0119a9cbff2c581fc0f2d966b77114b2c4")]

class A {}