weird. tried to clear the solution before rebuilding? force-restoring nuget packages? empty the bin directory entirely?

I had something similar and found different projects within the soltion had different versions of that package installed, updated the older one to match and that solved that issue once I also updated the other 5 packages where this happened.

I was running my own branch and merging in from what was temp8 every now and then when this happened. Put it down to being pre-release at that time (or a mistake I made somewhere along the way)

So at first, it was you own NuGet server messing with you (as I read on Slack).

Have you tried to run .\build\build.ps1 now so it can try to reset all the dependencies? Also delete \src\Umbraco.Web.UI\web.config since you've probably got the wrong bits in there now installed by the Offroad nuget server's dependencies.

In general, always a good idea if it doesn't work to try the build script.

I've got a big long reply with all the things I've tried in draft for all the other folks who might get this odd error. I think its my machine and what I'm doing not Umbraco's fault but I'll document it here in a bit in case anyone has this query issue and raise an issue on github for a few quirks I've found so it should "just work" for others in future.

Urgh. So learnt some things along the way.

• Deleted all my DLL's from the /bin folder.
• Had to rebuild the Umbraco.Web.UI project separately (right click on it in solution explorer and select "Rebuild" from the pop up menu).
• Ran the /build/build.ps1 file in a powershell window (this takes a long time btw)

That got rid of the error and got me to another error about ClientDependancy Logger! But that taught me some new stuff:

• Switching between a v7 branch and a v8 branch gets you in trouble. Seems there are lots of config files that are ignored and when you switch around they don't get over-written so you end up running v7 config on a v8 site. This to me shouldn't happen but I found a line on the quick start guide (https://github.com/umbraco/Umbraco-CMS/blob/dev-v8/.github/V8GETTINGSTARTED.md) that does warns me to do a fresh check out of v8! Stupid Pete. So I've now done a fresh check out of just the dev-v8 branch.
• I've run the build.ps1 file again a fresh and then rebuild all my DLL's in VS with a right click on the solution file in the solution explorer window and selecting "Rebuild"
• This got things working!

Thanks all.

Another option would be to add a dependency on the Microsoft.CodeDom.Providers.DotNetCompilerPlatform.BinFix package instead of the Microsoft.CodeDom.Providers.DotNetCompilerPlatform package. The .BinFix adds a target which copies the compilers in automatically before building.

It is just a different NuGet package. You would add it using the NuGet Package Manager or the package manager console, however you normally add NuGet packages to your project.

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