[Desktop] Browser crashes immediately on Ubuntu 18.04

Description

On Ubuntu 18.04, Brave 1.12.114, Chromium 84.0.4147.135, Brave browser crashes immediately after startup.

Steps to Reproduce

1. open terminal
2. type “brave-browser”

Actual result:

Empty browser screen appears for a split second, but closes right away.

In terminal, following error appears: [9150:9150:0826/083725.566634:ERROR:sandbox_linux.cc(374)] InitializeSandbox() called with multiple threads in process gpu-process.

/usr/bin/brave-browser: row 48: 9125 Unauthorized access to memory (SIGSEGV) (core dumped [memory image saved]) "$HERE/brave" "$@"

Expected result:

browser starts

Reproduces how often:

every time

Brave version (brave://version info)

1.12.114

Version/Channel Information:

• Can you reproduce this issue with the current release?
• Can you reproduce this issue with the beta channel?
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome? Chromium works fine by itself

Miscellaneous Information:

at first, the erroe was [2899:2899:0826/080738.832798:ERROR:vaapi_wrapper.cc(531)] The system version 1.1 should be greater than or equal to 1.5

[2899:2899:0826/080738.875141:ERROR:sandbox_linux.cc(374)] InitializeSandbox() called with multiple threads in process gpu-process.

after reinstalling libva2, the first part of error dissapeared.

purging brave-browser did not help

[janoskaz]

Great! beta version works! Thanks for all your help.

[bsclifton]

Thanks for the assist, @Martina-Neumayer 😄