Following along with Steve Smith’s “Your First ASP.NET 5 Application on a Mac”, I found myself frustrated that, despite all my efforts, the simple little sample project I was trying to get running just wouldn’t work due to a problem with restoring the project’s dependencies.
Retracing my steps
I opened up my scaffolded project using Visual Studio Code, and began the dependency restore process. But it failed. So I troubleshooted (troubleshot?), and it failed some more.
“Restore failed Unknown header: 3208085783″.
I found David Fowler’s “Diagnosing Dependency Issues with ASP.NET 5″, but none of the things he mentioned helped resolve my exact issue. But something he said, caused me to think:
Make sure your DNX and packages are on the same version “train”
My issue wasn’t with DNX, but with Mono.
Mis-matched Mono versions
When I followed the instructions for installing ASP.NET, I distinctly remember installing Mono using the installer package available at their website.
What I failed to realize, however, was that a while back (long enough ago to where it didn’t hit me until just a few minutes ago), I installed Mono using Homebrew.
So despite my efforts to install Mono using the installer package, the Mono that everything in my system was using was the one installed by Homebrew, which was version 3.10.
To resolve the issue, I went ahead and just ran
brew upgrade mono.
Verifying that Mono was successfully upgraded via a
mono --version command, I retried the dependency restoration in my scaffolded ASP.NET 5 application.
dnu restore produced a wonderfully green, “Restore complete”!