[BUG] Unable to use fab auth login in WSL

[JoshLuedeman]

Bug Description

When trying to do interactive login with WSL, you can't login because it can't launch a browser from WSL to obtain token. For some reason, it opens a File Explorer window.

fabric-cli version

1.5.0

Python version

3.10.12

Operating System

Linux

CLI Mode

Command line mode

Authentication Method

Interactive browser login

Steps to Reproduce

open Ubuntu WSL in Windows
run

fab auth login

WSL then opens a file explorer window

Expected Behavior

fab auth login
Press [Enter] to open https://azure.com/device/login and copy 'XXXX-1234' to your clipboard

FAILED: Got to URL manually and enter device code XXXX-1234

Actual Behavior

It opened File Explorer in Windows and sat waiting for a response from the website until I killed the session

Additional Context

na

Possible Solution

I recommend using an approach similar to Azure CLI where you can provide a session code in a browser to authenticate

[github-actions]

AI Assessment: Potential Bug

The report describes an incompatibility between the interactive browser login flow of the Fabric CLI and the WSL environment. The CLI appears to attempt to launch the default browser, which on WSL results in opening a Windows File Explorer window instead of prompting for device login or displaying a browser-based authentication flow. This behavior deviates from expected cross-platform CLI authentication standards and is inconsistent with patterns used by other Microsoft tools (e.g., Azure CLI's device code flow).

There is a risk that users on WSL or other headless environments cannot authenticate interactively, blocking use of the CLI unless alternative auth methods are used. This is not aligned with expected usability for a Python CLI operating in WSL. The issue occurs within command-line mode, not REPL, further supporting its severity.

Recommend the team evaluate implementing or defaulting to a device code prompt for environments where launching a browser is not possible (see RFC 6749 and MSAL guidance). This approach is used by Azure CLI and avoids platform-specific edge cases. The relevant documentation (https://microsoft.github.io/fabric-cli/commands/auth/) does not mention WSL or headless browser auth flows.

Next Steps
🔔 Escalated to team — This issue requires team review and has been flagged for attention.

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💡 If this issue requires the team's attention and was not escalated, you can tag @microsoft/fabric-cli-dev to notify the team.

[github-actions]

🔔 @microsoft/fabric-cli-dev — This issue has been flagged by AI triage as requiring team attention. Please review the assessment above.

[aviatco]

/triaged

[microsoft-github-policy-service]

Triage has been completed for this issue.

[aviatco]

@JoshLuedeman thanks for reporting this issue.

Browser launch is only partially supported in WSL
In WSL, there is no real Linux desktop environment:

• No native browser
• No xdg-open target
• No graphical session

So, when Fabric CLI tries to open a browser, Windows intercepts it in a best‑effort way, which is why you reported seeing File Explorer opening instead of a browser.

From WSL, you can login with Service Principal, Managed Identity or reuse a token obtained outside WSL.

A solution for this issue you reported is using device code authentication, though it's not yet supported. If you think it is a missing capability, please open a feature request issue with this ask.