System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at Microsoft.Build.BackEnd.SdkResolution.SdkResolverService.GetResolvers(IList`1 resolversManifests, LoggingContext loggingContext, ElementLocation sdkReferenceLocation)
   at Microsoft.Build.BackEnd.SdkResolution.SdkResolverService.ResolveSdkUsingResolversWithPatternsFirst(Int32 submissionId, SdkReference sdk, LoggingContext loggingContext, ElementLocation sdkReferenceLocation, String solutionPath, String projectPath, Boolean interactive, Boolean isRunningInVisualStudio)
   at Microsoft.Build.BackEnd.SdkResolution.SdkResolverService.ResolveSdk(Int32 submissionId, SdkReference sdk, LoggingContext loggingContext, ElementLocation sdkReferenceLocation, String solutionPath, String projectPath, Boolean interactive, Boolean isRunningInVisualStudio)
   at Microsoft.Build.BackEnd.SdkResolution.CachingSdkResolverService.<>n__0(Int32 submissionId, SdkReference sdk, LoggingContext loggingContext, ElementLocation sdkReferenceLocation, String solutionPath, String projectPath, Boolean interactive, Boolean isRunningInVisualStudio)
   at Microsoft.Build.BackEnd.SdkResolution.CachingSdkResolverService.<>c__DisplayClass3_0.<ResolveSdk>b__2()
   at System.Lazy`1.ViaFactory(LazyThreadSafetyMode mode)
--- End of stack trace from previous location ---
   at System.Lazy`1.CreateValue()
   at Microsoft.Build.BackEnd.SdkResolution.CachingSdkResolverService.ResolveSdk(Int32 submissionId, SdkReference sdk, LoggingContext loggingContext, ElementLocation sdkReferenceLocation, String solutionPath, String projectPath, Boolean interactive, Boolean isRunningInVisualStudio)
   at Microsoft.Build.Evaluation.Evaluator`4.ExpandAndLoadImportsFromUnescapedImportExpressionConditioned(String directoryOfImportingFile, ProjectImportElement importElement, List`1& projects, SdkResult& sdkResult, Boolean throwOnFileNotExistsError)
   at Microsoft.Build.Evaluation.Evaluator`4.ExpandAndLoadImports(String directoryOfImportingFile, ProjectImportElement importElement, SdkResult& sdkResult)
   at Microsoft.Build.Evaluation.Evaluator`4.EvaluateImportElement(String directoryOfImportingFile, ProjectImportElement importElement)
   at Microsoft.Build.Evaluation.Evaluator`4.PerformDepthFirstPass(ProjectRootElement currentProjectOrImport)
   at Microsoft.Build.Evaluation.Evaluator`4.EvaluateImportElement(String directoryOfImportingFile, ProjectImportElement importElement)
   at Microsoft.Build.Evaluation.Evaluator`4.PerformDepthFirstPass(ProjectRootElement currentProjectOrImport)
   at Microsoft.Build.Evaluation.Evaluator`4.Evaluate()
   at Microsoft.Build.Evaluation.Project.ProjectImpl.Reevaluate(ILoggingService loggingServiceForEvaluation, ProjectLoadSettings loadSettings, EvaluationContext evaluationContext)
   at Microsoft.Build.Evaluation.Project.ProjectImpl.ReevaluateIfNecessary(ILoggingService loggingServiceForEvaluation, ProjectLoadSettings loadSettings, EvaluationContext evaluationContext)
   at Microsoft.Build.Evaluation.Project.ProjectImpl.ReevaluateIfNecessary(ILoggingService loggingServiceForEvaluation, EvaluationContext evaluationContext)
   at Microsoft.Build.Evaluation.Project.ProjectImpl.ReevaluateIfNecessary(EvaluationContext evaluationContext)
   at Microsoft.Build.Evaluation.Project.ProjectImpl.Initialize(IDictionary`2 globalProperties, String toolsVersion, String subToolsetVersion, ProjectLoadSettings loadSettings, EvaluationContext evaluationContext)
   at Microsoft.Build.Evaluation.Project..ctor(ProjectRootElement xml, IDictionary`2 globalProperties, String toolsVersion, String subToolsetVersion, ProjectCollection projectCollection, ProjectLoadSettings loadSettings, EvaluationContext evaluationContext, IDirectoryCacheFactory directoryCacheFactory)
   at Microsoft.Build.Evaluation.Project.FromProjectRootElement(ProjectRootElement rootElement, ProjectOptions options)