var testUsers = _context.Users.AsNoTracking().Include(a => a.Company)
            .Where(a => a.Company != null && !string.IsNullOrEmpty(a.Company.Name) && a.Company.Name.Contains("E"));

testUsers = testUsers
            .Where(a => a.Company != null && !string.IsNullOrEmpty(a.Company.Name) && a.Company.Name.Contains("D"));

testUsers.ToList(); //Exception Message: must be reducible node

at System.Linq.Expressions.Expression.ReduceAndCheck()
at System.Linq.Expressions.Expression.ReduceExtensions()
at System.Linq.Expressions.Compiler.StackSpiller.RewriteExtensionExpression(Expression expr, Stack stack)
....