Originally posted by bzz:

You need to add -console to the launch options for Valheim.

Open Steam > Library > Right click on Valheim > Properties.
On that page you should see "Launch options" click on it and add -console

Not sure how it works for dedicated servers tho

1) The F5 console isn't necessary for forcing saves. You can also do it from the chat window [Enter] and issuing "/save" (without quotes).

2) Even with -console in the launch options, the console sometimes still won't come up when you press F5. If you encounter this problem, then alt-tab out of the game then alt-tab back in. This seems to fix it in my experience.

Either way, "Save" will only perform saves on client-controlled components - Character and world if you're playing local solo or hosting multiplayer through the client, Character only if playing through a dedicated server.