Bug 'SysrootPackage.GetSysrootPath()': no suitable method found to override

I put my main project of 5 years down for a month to play with some VR stuff... Having again worked on my main project these past few days I went to export a patch in Win64 and Linux64 but Linux is generating errors as soon as I target it:

Library\PackageCache\com.unity.sysroot@2.0.2\Editor\Unity.SysrootPackage.cs(155,20): error CS0115: 'SysrootPackage.GetSysrootPath()': no suitable method found to override
Library\PackageCache\com.unity.sysroot@2.0.2\Editor\Unity.SysrootPackage.cs(167,20): error CS0115: 'SysrootPackage.GetToolchainPath()': no suitable method found to override
Library\PackageCache\com.unity.sysroot@2.0.2\Editor\Unity.SysrootPackage.cs(179,20): error CS0115: 'SysrootPackage.GetIl2CppCompilerFlags()': no suitable method found to override
Library\PackageCache\com.unity.sysroot@2.0.2\Editor\Unity.SysrootPackage.cs(191,20): error CS0115: 'SysrootPackage.GetIl2CppLinkerFlags()': no suitable method found to override

I tried just commenting out the #IF flags setting them as overrides, but Unity rewrites the script every time I open it. I assume it's pulling from a local package database or something that got updated with my VR downloads? How do I fix this? =[

 

This was 2019.4.29. I upgarded to 2019.4.39 and the problem went away. I assume the package database (just the cache?) got corrupted or something.