Error CS1069: The type name ‘DataTable’ could not be found in the namespace ‘System.Data’

[chutminh0910 (MinhTran)]

When I update I have this problem, How to fix?
error CS1069: The type name ‘DataTable’ could not be found in the namespace ‘System.Data’. This type has been forwarded to assembly ‘System.Data.Common, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a’ Consider adding a reference to that assembly.
Error ERROR Validation Error (1,93): error CS0012: The type ‘IXmlSerializable’ is defined in an assembly that is not referenced. You must add a reference to assembly ‘System.Xml.ReaderWriter, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a’.

[loginerror (Maciej Kuźmicz)]

Hey @chutminh0910

Would you mind providing a zip of a sample (dummy) project that reproduces this issue?

[alexandru (Alexandru Roman)]

@chutminh0910 please save a copy of the faulty project and share it with us. Because of the improvements done for validation time some namespaces are not found in the xaml. We introduced a detection mechanism that is fired when doing Project Validation. We want to make sure that your case is also covered.

[chutminh0910 (MinhTran)]

Hi @alexandru @loginerror,
Thank you for your reply, sorry for reply late.
I don’t know about this issue, but I delete full foder have (.) front (ex: .local,…)

So, Current Project Run, but I dont know about this result.

[alexandru (Alexandru Roman)]

Never do that. All folders created by Studio are needed.

You can easily make your project unusable.