I've also been running into this error rather frequently. It's resulted in some temporary bans and I've gone through extensive troubleshooting. Upon crashing I get stuck in "Downloading" which often requires a full re-install of the game, or waiting 10+ minutes and then the steamworks common redistributibles install and finally deadlock starts the "Downloading" again.
- Fresh install
- Removing just the pak_01 files and validating the game
- Replacing citadel folder with a known working one of a friend
- Replaced my DRAM completely after seeing that it had some errors
- Turning off DOCP
- Changing clock speed to 3200 (Most stable for AM4 chips)
Ultimately even if it becomes stable for an evening, as soon as a hotfix comes out the game breaks again. I've only started running into this issue shortly after the last batch of characters came out (billy, calico, holliday, etc). However since the new big patch came out it's gotten way worse and I'm on my second temporary ban.
It's a pretty frustrating way to spend the night after a crappy work week (every week) but it doesn't feel like Valve is listening to any of us running into this error, or at least I haven't seen any comments from the forum mods/game devs recognising the the wrongful temp bans and overall frustration it can bring to us and other when a match gets ruined.