Flutter Inspector "Disconnected" when trying to open it in Android Studio, VS Code, and the web browser

• Issue occurs in Android Studio, VS Code, and when opening Dart DevTools in the browser from VS Code
• Also occurs when running the app on an emulator and on a physical device. The same message is shown in the Inspector window for all of them.
• I have checked everything I can, and have Googled the issue. Other people are having similar issues with DevTools, but not this specific one from what I've found. I've tried some solutions which I thought could be relevant - nothing has worked.
• This was not happening the last time I used Flutter a couple of months ago. I have installed the latest updates since. Other than that, no changes on my end.
• See screenshot

This was a bug in a recent release of DevTools that didn't gracefully handle versions of Flutter that were missing a new API:

https://github.com/flutter/devtools/issues/2648

This issue was fixed in version 0.9.7+2 of DevTools, which VS Code should automatically update to. If it doesn't, you can manually update with:

pub global activate devtools

Note: do not include a flutter prefix.

If pub isn't in your PATH you may need to run it with a full path like:

(flutter SDK)\bin\cache\dart-sdk\bin\pub global activate devtools