title: How to build an external class library for use with a solution in a CI Pipeline in Azure DevOps?
body: <p>I've requested to my Team Lead that we start integrating a CI/CD pipeline into most, if not all, of our projects. Our newest project relies heavily on our own, external class library that is referenced in the solution ; it is under "Dependencies" as a project reference.</p>
  
  <p>The project runs fine when I build it in my machine using Visual Studio 2019, and before we needed to integrate an external library, it would build and release fine using our Azure DevOps pipelines.</p>
  
  <p>However, with the addition of an external class library, when I try to run a build through Azure DevOps, I get the following error:</p>
  
  <blockquote>
    <p>The project file  ....csproj was not found.</p>
  </blockquote>
  
  <p>I fully understand why it can't find it - because I need to pull in the external class library and build that first! There doesn't seem to be a lot of online material (not that I could find anyway!) that describes solutions to this other than "use nuget" ; unfortunately, it is a requirement from my Team Lead that this is not a route we go down - which has lead to a long couple of days!</p>
  
  <p>With this in mind, I can't find another way to do this in Azure DevOps. I have looked into some sort of PowerShell command but to no avail thus far.</p>
  
  <p>Has anyone run into this issue before with external class libraries in DevOps and can give me advice on the best way to approach it?</p>