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|
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, types, members||Delete|
|Generics||Add or modify|
|Types||Add abstract or virtual member, add override (see details)|
|Members||Modify a member referencing an embedded interop type|
|Members||Modify a static member after it has already been accessed by executing code|
|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||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|
|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)|
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
Unsupported app scenarios
Unsupported apps and platforms include ASP.NET 5, Silverlight 5, and Windows 8.1.
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).
Edit and Continue is not available in the following debugging scenarios:
Mixed-mode (native/managed) 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.