MSB4018: The task failed unexpectedly

This error is emitted when a task fails with an unhandled exception. This is generally a sign of a bug in the task.

Error MSB4018 may be caused when running a task in an environment that it was not prepared for, for instance when a task has an x86 dependency but is running in a 64-bit MSBuild environment. This can manifest as a System.DllNotFoundException.

S:\BitnessInMSBuild\ShowErrors.proj(6,7): error MSB4018: The "AnyCPUTaskWithPInvoke" task failed unexpectedly.
S:\BitnessInMSBuild\ShowErrors.proj(6,7): error MSB4018: System.DllNotFoundException: Unable to load DLL 'Native32BitLibrary.dll': The specified module could not be found. (Exception from HRESULT: 0x8007007E)
S:\BitnessInMSBuild\ShowErrors.proj(6,7): error MSB4018:    at AnyCPUTaskWithPInvoke.AnyCPUTaskWithPInvoke.NativeMethod()
S:\BitnessInMSBuild\ShowErrors.proj(6,7): error MSB4018:    at AnyCPUTaskWithPInvoke.AnyCPUTaskWithPInvoke.OtherMethod() in S:\BitnessInMSBuild\AnyCPUTaskWithPInvoke\AnyCPUTaskWithPInvoke.cs:line 19
S:\BitnessInMSBuild\ShowErrors.proj(6,7): error MSB4018:    at AnyCPUTaskWithPInvoke.AnyCPUTaskWithPInvoke.Execute() in S:\BitnessInMSBuild\AnyCPUTaskWithPInvoke\AnyCPUTaskWithPInvoke.cs:line 12
S:\BitnessInMSBuild\ShowErrors.proj(6,7): error MSB4018:    at Microsoft.Build.BackEnd.TaskExecutionHost.Microsoft.Build.BackEnd.ITaskExecutionHost.Execute()
S:\BitnessInMSBuild\ShowErrors.proj(6,7): error MSB4018:    at Microsoft.Build.BackEnd.TaskBuilder.<ExecuteInstantiatedTask>d__26.MoveNext()

To resolve this, ensure that the task expresses a dependency on the runtime environment it requires in the task's UsingTask element.