How can this Visual studio Resource warning be resolved or removed?

In Visual Studio 2017 I had the same issue with the following error

Warning A custom tool 'ResXFileCodeGenerator' is associated with file <snip name>, but the output of the custom tool was not found in the project. 

Removing the reference to <Generator>ResXFileCodeGenerator</Generator> within the resource file declaration, fixed the issue.

In my case this was caused by a <LastGenOutput> entry in the csproj file that referred to a non-existent file. Removing that line got rid of the warning.

After checking out the csproj file and discussing it in the group, we came up with the following answer:

When the resources were added to the project they were added using the wizard. This wizard added the designer files also, so for each reasource file there was also a .designer file.

This was seen as something that was not needed for the language specific resources and the designer files were deleted.

However the csproj files maintained the custom tool reference.

Deleting this reference (to "GlobalResourceProxyGenerator") for each of these resource files removed the issue.

The issue is that Visual Studio 2010 does not automatically remove this tool reference when the designer files are removed manually, creating this warning.