In a surprising move, Microsoft has rendered its C/C++ extension for Visual Studio Code (VS Code) unusable in popular forks like VS Codium and Cursor, sparking an uproar among developers.

In early April, developers using VS Codium, an open-source alternative to Microsoft's VS Code, and Cursor, an AI coding assistant based on the same codebase, found that the beloved C/C++ extension had suddenly ceased to function.

This extension is crucial, providing essential support for C/C++ language features like Intellisense code completion and debugging. Its removal from these derivative tools disrupts developers' workflows and raises serious competition concerns.

The issue started with an update on April 3, 2025, when version 1.24.5 was released. Since then, any attempts to install the C/C++ extension on non-Microsoft environments result in a frustrating error message, restricting its use solely to Microsoft’s products.

While Microsoft has enforced these restrictions on its extensions since September 2020, it is only now that the company has implemented checks in the C/C++ extension to prevent its use outside of its own software.

Interestingly, Microsoft's PyLance extension for Python has been facing similar barriers for years, thus hinting at broader implications for developers using any Microsoft tools.

Michael Truell, co-founder and CEO of Cursor, acknowledged the problem in a discussion recently, revealing that they have deployed a temporary fix and are working on a long-term solution. "We are transitioning away from these closed-source extensions and investing in open-source alternatives that we'll bundle into the next version to ensure a smooth transition," he stated.

Cursor has reportedly been pushing the boundaries of Microsoft’s terms by using workarounds to allow users to install VS Code extensions directly from Microsoft's marketplace, whereas other VS Code alternatives typically source extensions from the Open VSX marketplace.

Developers using VS Codium are now on the hunt for free and open-source replacements, viewing this issue as a significant limitation on their coding capabilities.

In the backdrop, discussions have emerged among developers regarding Microsoft’s potential anti-competitive practices; some even have reached out to the U.S. Federal Trade Commission, alleging unfair competition tactics and self-preferencing with the rollout of Microsoft’s Copilot features.

As Microsoft remains tight-lipped regarding these allegations, the developer community is keenly observing how the situation unfolds, with the tension between open-source ideals and corporate strategies at an all-time high.