WharfsyncFix “TypeError: isDate is not a function” in the VS Code SFTP extension
Since VS Code 1.124 (June 2026), the Natizyskunk SFTP extension fails with TypeError: isDate is not a function. Upload on save stops working.
Why it happens
VS Code 1.124 runs extensions on a newer version of Node.js, which removed old helper functions such as util.isDate. A library bundled inside the SFTP extension still calls it. The extension has not been updated since 2023, so the call was never replaced.
Your options
- Downgrade VS Code to 1.122. This works, but you give up security updates for your editor.
- Hand-patch the installed extension. This breaks again every time the extension or VS Code updates, and a patched extension is easy to get wrong.
- Switch to a maintained extension that reads the same
.vscode/sftp.json.
Switching to Wharfsync
Wharfsync is a clean-room rewrite that reads the same sftp.json format, so your hosts, contexts, profiles and ignore lists carry over. It is tested on current VS Code, Insiders, Cursor and VSCodium, and every build is checked for the removed Node functions that caused this error. It is free for one server profile.
While you are moving, it also fixes the other long-standing complaint: passwords in sftp.json. Wharfsync offers to move them into your OS keychain, and it never uploads .vscode/ to your server.
Wharfsync is independent and not affiliated with the authors of the SFTP extension.