CA1903: Use only API from targeted framework

Applies to: Visual Studio Visual Studio for Mac

Note

This article applies to Visual Studio 2017. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here

Item	Value
RuleId	CA1903
Category	Microsoft.Portability
Breaking change	Breaking - when fired against the signature of an externally visible member or type. Non-Breaking - when fired in the body of a method.

Cause

A member or type is using a member or type that was introduced in a service pack that was not included with the project's targeted framework.

Note

This rule has been deprecated. For more information, see Deprecated rules.

Rule description

New members and types were included in .NET Framework 2.0 Service Pack 1 and 2, .NET Framework 3.0 Service Pack 1 and 2, and .NET Framework 3.5 Service Pack 1. Projects that target the major versions of the .NET Framework can unintentionally take dependencies on these new APIs. To prevent this dependency, this rule fires on usages of any new members and types that were not included by default with the project's target framework.

Target Framework and Service Pack Dependencies

Item	Value
When target framework is	Fires on usages of members introduced in
.NET Framework 2.0	.NET Framework 2.0 SP1, .NET Framework 2.0 SP2
.NET Framework 3.0	.NET Framework 2.0 SP1, .NET Framework 2.0 SP2, .NET Framework 3.0 SP1, .NET Framework 3.0 SP2
.NET Framework 3.5	.NET Framework 3.5 SP1
.NET Framework 4	N/A

To change a project's target framework, see How to: Target a version of .NET.

How to fix violations

To remove the dependency on the service pack, remove all usages of the new member or type. If this is a deliberate dependency, either suppress the warning or turn off this rule.

When to suppress warnings

Do not suppress a warning from this rule if this was not a deliberate dependency on the specified service pack. In this situation, your application might fail to run on systems without this service pack installed. Suppress the warning or turn off this rule if this was a deliberate dependency.

Example

The following example shows a class that uses the type DateTimeOffset that is only available in .NET 2.0 Service Pack 1. This example requires that .NET Framework 2.0 has been selected in the Target Framework drop-down list in the Project properties.

using System;
namespace Samples
{
    public class LibraryBook
    {
        private readonly string _Title;
        private DateTimeOffset _CheckoutDate;   // Violates this rule
        public LibraryBook(string title)
        {
            _Title = title;
        }
        public string Title
        {
        get { return _Title; }
        }
        public DateTimeOffset CheckoutDate      // Violates this rule
        {
            get { return _CheckoutDate; }
            set { _CheckoutDate = value; }
        }
    }
}

The following example fixes the previously described violation by replacing usages of the DateTimeOffset type with the DateTime type.

using System;
namespace Samples
{
    public class LibraryBook
    {
        private readonly string _Title;
        private DateTime _CheckoutDate;
        public LibraryBook(string title)
        {
            _Title = title;
        }
        public string Title
        {
            get { return _Title; }
        }
        public DateTime CheckoutDate
        {
            get { return _CheckoutDate; }
            set { _CheckoutDate = value; }
        }
    }
}

See also

• Framework targeting overview