Your system information

Linux Mint 19.1

• Steam client version (build number or date): Latest Steam beta
• Distribution (e.g. Ubuntu): Mint 19.1
• Opted into Steam client beta?: Yes
• Have you checked for system updates?: Yes

Please describe your issue in as much detail as possible:

It doesn't login anymore.

steam output:

https://gist.github.com/Leopard1907/70cfcd07169118d72ba045a7dbb0480d

Steps for reproducing this issue:

1. Steam Beta Client
2. Linux
3. An internet connection