How To Fix Visual Studio Package Not Restore
Today, I was busy working on one of the WPF apps that I have been developing over the last few days. Everything was going fine; I had even made a Release build two days ago on the 11th of July.
Suddenly, I needed to hand the project over to another developer. I deleted the package folder, handed over the code, came back, switched my build configuration to Release, and attempted to compile. Boom, the compile failed.
Suddenly, my main XAML file (specifically the Splash screen) also failed to work. This happened in the morning and could have been a disaster since I had just finished my work. I restored the package folder from the Recycle Bin, but still, nothing would compile.
At first, I went into `splash.xaml.cs` and manually imported all the required namespaces (I am not sure how they got removed just by switching to the Release configuration).
The root cause in my case was:
NuGet.org (the NuGet Gallery) did not have any information about version 1.0.3 (from 2016), causing the package restore from the NuGet site to fail. I noticed that the `.csproj` file still referenced version 1.0.3. I upgraded the package to version 1.0.8 (which is the latest version), but Visual Studio did not clean up the 1.0.3 reference from the `.csproj` file and failed to resolve it. Although my project was supposed to reference the 1.0.8 SQLite DLL, it was still pointing to version 1.0.3.
This meant:
Version 1.0.3 would not be copied to my output directory since the package folder was empty, missing, or did not contain that DLL.
Visual Studio wasn't able to resolve this automatically because the package didn't exist anymore. I'm not sure how VS handles this internally; perhaps it assumed the reference was local on my system.
The Fix
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I uninstalled version 1.0.3. Unfortunately, Visual Studio did not remove the 1.0.3 reference from the `.csproj` file (where it was actually mentioned twice). I had to open the `.csproj` file in a text editor and remove the references manually.
I then installed version 1.0.8 of SQLite in my WPF C# project, and now everything works beautifully. If you ever get stuck in a similar situation, it is always a good idea to keep a backup (or use a Git repository). Additionally, learning how `.csproj` files are structured is incredibly helpful when troubleshooting reference issues like this.
A few days ago, I was stuck on a Xamarin issue where the compiled code (XAML, C#, UWP) did not match the code I actually had. Later, I got help from Nico on Stack Overflow, and everything started running flawlessly.
Here is the reference to that helpful answer: https://stackoverflow.com/a/51166764/713789