Reference DLL file not copying to bin with deployment project, causing error

Question

We have several external DLL files being referenced in our Web Application Project. We have a deployment project for installing on the hosting servers. When we were using .N

Answer 1

I just had the same issue and wanted to share what I found as it might help someone:

The reason in my case was that the assembly was installed in the GAC during an installation of some third-party application.

If the DLL file is in the GAC, the compiler won't bother to copy it to the destination folder, unless you specifically mark it for "copy local" using the "Private" node in the project file as mentioned by Junto.

The thing is that if you don't add that node, and you develop on one machine and build on a different one, and the DLL file is only in the GAC of the build machine, the default behavior without the private node will cause the file to be copied correctly on the development machine, but not on the build machine.

The bigger problem is if the DLL file is not referenced directly, but the project references a second project that in turn references the DLL file. In that case, you cannot mark the DLL file to be "copy local" in the project, as it is not referenced by it. So if the DLL file exists in the GAC - it won't get copied to your output folder.

Possible solutions to this case are:

• Uninstall the DLL file from the GAC
• Add a direct reference to the DLL file in the end project(s)
• Re-sign the DLL file with a new strong name, which will differentiate it from the DLL file in the GAC.