21 down vote I had the same problem with TeamCity 10.0.1 (build 42078) and NUnit 3.4.1. And it turned out to be completely my fault. I’m posting it here as someone else can stumble into the same problem and this can save them some time. It turned out that the problem was in the “Run tests from: ” setting in my build configuration. I had **\*.Test.dll. That was accidentally picking up dlls for \obj\**\ directories (where there is no nunit.framework.dll present). Once I changed the setting to **\bin\%Bui
Source: .net – NUnit 3.2.1 + TeamCity: Could not load file or assembly ‘nunit.framework’ – Stack Overflow