[223] Adding an existing project

I was adding an existing project to the solution, after have selected the .csproj I have got this exception:

 System.NullReferenceException: Object reference not set to an instance of an object.
   at JetBrains.ReSharper.Util.HashSet.AddAll(ICollection other) in c:\TEMP\tmp5613.tmp\src\Util\src\dataStructures\HashSet.cs:line 56
   at JetBrains.ReSharper.Psi.Impl.Caches2.SymbolCache.OnProjectPropertiesChanged(IProject project, HashSet affectedFiles) in c:\TEMP\tmp5613.tmp\src\Psi\src\impl\caches2\symbolCache\SymbolCache.cs:line 969
   at JetBrains.ReSharper.Psi.Impl.Caches2.CompositeCache.OnProjectPropertiesChanged(IProject project, HashSet affectedProjectFiles) in c:\TEMP\tmp5613.tmp\src\Psi\src\impl\caches2\CompositeCache.cs:line 63
   at JetBrains.ReSharper.Psi.Impl.Caches2.MyChangeProcessor.ProcessProject(IProject project) in c:\TEMP\tmp5613.tmp\src\Psi\src\impl\caches2\PsiCacheManagerImpl.cs:line 461
   at JetBrains.ReSharper.Psi.Impl.Caches2.MyChangeProcessor.ProcessChangeUnit(IChangeUnit changeUnit, IDictionary temporaryData) in c:\TEMP\tmp5613.tmp\src\Psi\src\impl\caches2\PsiCacheManagerImpl.cs:line 441
   at JetBrains.ReSharper.Shell.Impl.MyChangePropagationHelper.VisitProvider(IChangeProvider changeProvider, IChangeProcessor[] dependentProcessors) in c:\TEMP\tmp5613.tmp\src\Shell\src\impl\changes\ChangeManagerImpl.cs:line 267
   at JetBrains.ReSharper.Shell.Impl.MyGraphVisitor.VisitNode(IChangeProvider changeProvider) in c:\TEMP\tmp5613.tmp\src\Shell\src\impl\changes\ChangeManagerImpl.cs:line 152
   at JetBrains.ReSharper.Shell.Impl.MyChangePropagationHelper.Run(IProgressIndicator progressIndicator) in c:\TEMP\tmp5613.tmp\src\Shell\src\impl\changes\ChangeManagerImpl.cs:line 207
   at JetBrains.ReSharper.Shell.Progress.AsyncTaskHelper.ThreadFunc() in c:\TEMP\tmp5613.tmp\src\Shell\src\Progress\ProgressWindow.cs:line 477
   --- End of inner exception stack trace ---

	at JetBrains.ReSharper.Util.Logger.LogExceptionEx(Exception, String, Boolean) in c:\TEMP\tmp5613.tmp\src\Util\src\Logger.cs:line 297 column 9
	at JetBrains.ReSharper.Util.Logger.LogException(Exception) in c:\TEMP\tmp5613.tmp\src\Util\src\Logger.cs:line 309 column 5
	at JetBrains.ReSharper.Shell.Progress.AsyncTaskHelper.ThreadFunc() in c:\TEMP\tmp5613.tmp\src\Shell\src\Progress\ProgressWindow.cs:line 485 column 11

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