TeamCity builds failing after server migration and upgrade

We have a TC Build server that we are migrating off of.

All the builds work there.

We made a new server, migrated all the build configurations, but now none of the builds work.

All are failing with strange error messages about not being able to find things... though the builds all can't find differnt things.

..."error CS0234: The type or namespace name 'VisualStudio' does not exist in the namespace 'Microsoft'"

..."C:\Program Files (x86)\MSBuild\14.0\bin\Microsoft.Common.CurrentVersion.targets(2828, 5): error MSB3086: Task could not find "LC.exe" using the SdkToolsPath "" or the registry key "HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SDKs\NETFXSDK\4.6\WinSDK-NetFx40Tools-x86". Make sure the SdkToolsPath is set and the tool exists in the correct processor specific location under the SdkToolsPath and that the Microsoft Windows SDK is installed"

..."Services\EvidenceCollectionService.cs(5, 18): error CS0234: The type or namespace name 'Http' does not exist in the namespace 'System.Web' (are you missing an"

All the builds are working on the original server, and stuff is working locally.  

help!