PostgreSQL solution build failing in Visual Studio 2019 Community version

[vidur]

Errors while trying to build the solution.

The type or namespace name 'IOverClause' could not be found (are you missing a using directive or an assembly reference?) EntitySpaces.ORM.PostgreSQL (net451), EntitySpaces.ORM.PostgreSQL (net461), EntitySpaces.ORM.PostgreSQL (netcoreapp2.0), EntitySpaces.ORM.PostgreSQL (netcoreapp3.0), EntitySpaces.ORM.PostgreSQL (netstandard2.0)

Character ' ', hexadecimal value 0x3 is illegal in XML documents. EntitySpaces.ORM.PostgreSQL

[softwareschreiber]

same problem in other projects like MySql