Users of Cursor, an AI coding editor based on the same open source foundation as Microsoft’s Visual Studio Code (VS Code), are experiencing new problems with popular Microsoft extensions, such as for C and C++.

A developer complained that the “C/C++ extension is broken” although this worked previously. Reports state that version 1.17.62 works but 1.18.21 and later do not.

Microsoft’s terms for the VS Code extension marketplace state that it may only be used with “in-scope products and services,” these being Visual Studio, VS Code, GitHub Codespaces, Azure DevOps and Azure DevOps Server. The restrictions on the use of the official marketplace give developers an incentive to use Microsoft’s official distribution rather than others. The lock-in this represents resulted in the creation of the Open VSX marketplace, now managed by the Eclipse Foundation, on the grounds that without it the official VS Code-only marketplace would “severely restrict the capabilities of organizations that have adopted open source developer tools.”

That said, the Open VSX marketplace has many fewer extensions and lower usage than Microsoft’s marketplace. Anysphere’s Cursor nevertheless provides access to VS Code marketplace extensions including Microsoft’s C/C++ extension and the C# DevKit, from within the Cursor IDE, as well as a setup option to import extensions from a VS Code installation.

It appears that Microsoft is now enforcing its terms more rigorously. DevClass was able to install Microsoft’s C/C++ extension from within Cursor, but attempting to use a feature such as Find all references did not work, and eventually we saw a pop-up notice advising of the extension’s restrictions.

It is confusing, since Cursor still shows a recommendation that developers install Microsoft’s C++ extension when it encounters a suitable project. Developers may consider an alternative such as the clangd extension though note that it has only 1.7 million installs, versus 81 million for Microsoft’s offer.

Cursor’s documentation also provides instructions on how to install any extension from the Microsoft store. This feature depends on downloading the extension as a .vsix file; however the link for this no longer appears in the home page for the extension within the marketplace. In many cases, if the extension is open source,  developers can download this from its repository, such as on GitHub. 

Some developers have speculated that this changed behavior has been prompted by the arrival of Agent Mode in the stable build of VS Code, an AI-driven feature that makes Cursor a more direct competitor.

Microsoft has long said that although the code for Code-OSS is open source under the MIT license, VS Code is “a distribution of the Code – OSS repository with Microsoft-specific customizations released under a traditional Microsoft product license.”

A comment on the compliance aspect of using Cursor with VS Code marketplace extensions noted that Cursor likely does not link directly to themarketplace, but publishes the links to published extensions via its own service. The new issues appear to be restricted to Microsoft’s own extensions, not those from third-parties.