Use the activity log

VSPackages can write messages to the activity log. This feature is especially useful for debugging VSPackages in retail environments.


The activity log is always turned on. Visual Studio keeps a rolling buffer of the last 100 entries as well as the first 10 entries, which have general configuration information.

To write an entry to the activity log

  1. Insert this code in the Initialize method or in any other method except the VSPackage constructor:

    IVsActivityLog log = GetService(typeof(SVsActivityLog)) as IVsActivityLog;
    if (log == null) return;
        "Called for: {0}", this.ToString()));

    This code gets the SVsActivityLog service and casts it to an IVsActivityLog interface. LogEntry writes an informational entry into the activity log using the current cultural context.

  2. When the VSPackage is loaded (usually when a command is invoked or a window is opened), the text is written to the activity log.

To examine the activity log

  1. Run Visual Studio with the /Log command line switch to write ActivityLog.xml to disk during your session.

  2. After closing Visual Studio, find the activity log in the subfolder for Visual Studio data:


  3. Open the activity log with any text editor. Here's a typical entry:

    Called for: Company.MyApp.MyAppPackage ...

Troubleshooting Import/Export Issues in Editor Extensions: Access the MEF Composition Error Log

When writing an editor-based extension, you may experience issues if you try to import something that doesn't exist in the current VS install, or if you incorrectly author your import or export. The primary way to find and address these issues is to reference the Managed Extensibility Framework (MEF) Composition Error Log, stored at %localappdata%\Microsoft\VisualStudio{version}\ComponentModelCache\Microsoft.VisualStudio.Default.err. To learn more about using MEF in your extensions, check out this documentation.

Robust programming

Because the activity log is a service, the activity log is unavailable in the VSPackage constructor.

You should obtain the activity log just before writing to it. Don't cache or save the activity log for future use.