Supported code changes (C# and Visual Basic)

Edit and Continue handles most types of code changes within method bodies. Most changes outside method bodies, and a few changes within method bodies, cannot be applied during debugging, however. To apply those unsupported changes, you must stop debugging and restart with a fresh version of the code.

Supported changes to code

The table below shows the changes that may be made to C# and Visual Basic code during a debugging session without restarting the session.

Language element/feature Supported edit operation Limitations
Types Add methods, fields, constructors, et al Yes
Iterators Add or modify No
async/await expressions Add or modify Yes
Dynamic objects Add or modify No
lambda expressions Add or modify Yes
LINQ expressions Add or modify Same as lambda expressions

Note

Newer language features such as string interpolation and null-conditional operators are generally supported by Edit and Continue. For the most current information, see the Enc Supported Edits page.

Unsupported changes to code

The following changes cannot be applied to C# and Visual Basic code during a debugging session:

  • Changes to the current statement or any other active statement.

    Active statements include any statements, in functions on the call stack, that were called to get to the current statement.

    The current statement is marked by a yellow background in the source window. Other active statements are marked by a shaded background and are read-only. These default colors can be changed in the Options dialog box.

  • The following table shows unsupported changes to code by language element.

Language element/feature Unsupported edit operation
All code elements Renaming
Namespaces Add
Namespaces, types, members Delete
Generics Add or modify
Interfaces Modify
Types Add abstract or virtual member, add override (see details)
Types Add destructor
Members Modify a member referencing an embedded interop type
Members (Visual Basic) Modify a member with On Error or Resume statement
Members (Visual Basic) Modify a member containing an Aggregate, Group By, Simple Join, or Group Join LINQ query clause
Methods Modify signatures
Methods Make an abstract method become non-abstract by adding a method body
Methods Delete method body
Attributes Add or modify
Events or properties Modify a type parameter, base type, delegate type, or return type
Operators or indexers Modify a type parameter, base type, delegate type, or return type
catch blocks Modify when it contains an active statement
try-catch-finally blocks Modify when it contains an active statement
using statements Add
async methods/lambdas Modify an async method/lambda in a project targeting .NET Framework 4 and lower (see details)
Iterators Modify an iterator in a project targeting .NET Framework 4 and lower (see details)

Unsafe code

Changes to unsafe code have the same limitations as changes to safe code, with one additional restriction: Edit and Continue does not support changes to unsafe code that exits within a method that contains the stackalloc operator.

Unsupported app scenarios

Unsupported apps and platforms include ASP.NET 5, Silverlight 5, and Windows 8.1.

Note

Apps that are supported include UWP in Windows 10, and x86 and x64 apps that target the .NET Framework 4.6 desktop or later versions (the .NET Framework is a desktop version only).

Unsupported scenarios

Edit and Continue is not available in the following debugging scenarios:

  • Mixed-mode (native/managed) debugging.

  • SQL debugging.

  • Debugging a Dr. Watson dump.

  • Debugging an embedded runtime application.

  • Debugging an application using attach to process (Debug > Attach to Process) instead of running the application by choosing Start from the Debug menu.

  • Debugging optimized code.

  • Debugging an old version of your code after a new version failed to build because of build errors.

See Also

Edit and Continue (Visual C#)
How to: Use Edit and Continue (C#)