Microsoft deprecated TLS 1.0 and TLS 1.1, which can cause connection failures when using the app.
Force the newer version of TLS on your machine
A PowerShell script from the Microsoft DevBlog that forces the newer version of TLS on your machine should resolve the connection issue.
Please try the script below:
# Set strong cryptography on 64-bit .NET Framework (version 4 and above)
Set-ItemProperty -Path 'HKLM:\SOFTWARE\Wow6432Node\Microsoft\.NetFramework\v4.0.30319' -Name 'SchUseStrongCrypto' -Value '1' -Type DWord
# Set strong cryptography on 32-bit .NET Framework (version 4 and above)
Set-ItemProperty -Path 'HKLM:\SOFTWARE\Microsoft\.NetFramework\v4.0.30319' -Name 'SchUseStrongCrypto' -Value '1' -Type DWord
Once the script completed, you can close PowerShell and restart the ShareGate migration tool (make sure you close the app from the system tray if it is active).
For more troubleshooting information, see Microsoft's article Authentication errors occur when client doesn't have TLS 1.2 support.
If it does not work
If you still get a failed connection, you can follow the the ShareGate migration tool connection troubleshooting guide that matches your scenario below: