This works on a Linux system and should work on Windows as well but I can't test it.

Sadly unless you alerady have a backup of a working version of the game this won't help much.

So,once you get Valheim working set the files in the Valheim game folder to "read-only" and make a backup.

The read-only will keep Steam from updating the game or applying any of hte little hotfixs that get sent out every so often. The world and character files are in a different directory and won't be effected.

BUT when a full update like todays rolss out Steam tries harder to apply an update and will report a disk write failure and not let you start the game. This is where the back up comes in to play. change the atributes of the Valheim game folder back to read/write and let Steam update the game. THis is so the Steam client THINKS the most recent update has been applied since it keeps track of it in a file somewhere other than the Valheim folder.

After Steam has updated the game delete the folder and replace it with the game folder in teh backup you made earlier. After that checnge the folder to read only again and enjoy the game.

NOTE: if you use mods be sure to keep the BepInEX folder writable so the mods can update/create their config files in teh BepInEX folder.

Yes it is a hassle to do this but it keeps the game playable while the devs at IG figure out how to actually program. I'm still playing version .209 with all my mods installed and likely will remain at that version for the near future.

Hope this is useful to someone else..