Signing in via browser fails when ArcGIS Pro is installed on a per-user basis, uninstalled, and reinstalled as a per-machine installation.

Workaround

To resolve the issue, open Windows Registry Editor and rename the key Computer\HKEY_CURRENT_USER\Software\Classes\arcgis-pro\shell\open\command:

to _command:

The proper registry key is generated when starting ArcGIS Pro again and signing in completes as expected. Attached is a video demonstrating this workflow.

Steps to Reproduce