How to use the Flutter doctor diagnostics tool in the right way

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If you are not feeling well, you go and see a doctor. The same goes for Flutter.

The Flutter diagnostics tool helps you identify configuration problems that might hinder a successful development workflow. As the output can be very helpful, it is required to include a diagnostic summary in every bug report in the official Flutter GitHub repository. Let’s have a look at the tool and its results.

Calling the doctor

Run the command flutter doctor from your preferred command-line tool. Your output might look similar to this one:

Screenshot of diagnostics output by author
Screenshot of diagnostics output by author

The tool lists information about

? Flutter and OS version
? Possible dependency problems with the Android toolchain
? Development tools like Chrome, Visual Studio, and Android Studio
? Connected devices that you can deploy your app to

As I am on a Windows machine right now, there is no information about any Linux, iOS, or macOS errors because I can’t create these app types from a Windows OS. So if you are on Linux or macOS, your output might look different.

In case of errors, you’ll typically get a detailed error message that points you towards a solution. Common problems involve Android toolchain errors, Android license errors, or no connected devices.

Calling the chatty doctor

Run the command flutter doctor -v from your preferred command-line tool. Your output might look similar to this one:

Screenshot of diagnostics output by author
Screenshot of diagnostics output by author

Compared to the previous output, we receive a lot more information and details for every group. The command tends to run twice as long as the other one to gather all the additional facts. SDK paths, install locations, plugin and tool version information, recognized devices including deployment targets and version info, and much more.

The doctor came, shoveled a lot of information upon you, and then left again. If you don’t see an error here, if you spot all your devices (browsers, phones, emulators, desktop platforms), and if all your IDEs are found, you’ll be fine.

Conclusion

Flutter doctor is the first source for solving problems when you are experiencing strange behavior and error messages. It is part of the initial Flutter setup and will also be executed on every version upgrade. With this article, you might understand the details better.

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