Can't Sign In - Error 400 (The server cannot process the request because it is malformed.)

[macksimumj]

Describe the bug
After entering email to link account, clicking next returns an error code 400 The server cannot process the request because it is malformed..

To Reproduce

1. Click 'Sign In'
2. Enter email.
3. Click 'Next'

Expected behavior
I expected to be allowed to enter my password and finish the sign in process.

Screenshots

Desktop (please complete the following information):
-Win 10/Win 11 (Bug still occurring after install of Win 10)
-Latest Release (5.6.0)

Additional context
QR code pairing works fine.

[Caspid]

Same issue here.

Just a note for anyone else having trouble migrating from the web app: if you can't scan the QR code as Google Messages no longer has a QR code scanner under Device Pairing — you need to sign out of all devices first, then select the option for QR pairing.