Can't connect to any server

[ATMunn]

For some reason, whenever I attempt to connect to a server, I get this error:

Mods mismatch detected!
base: Mod contents are different even though versions are the same

Any idea why this might be?

[noliVe]

you want to connect to a server with different mods

you think you have the same but the owner changed something inside it. ASK whats that about and get his modified mods to connect.

[ATMunn]

you want to connect to a server with different mods

you think you have the same but the owner changed something inside it. ASK whats that about and get his modified mods to connect.

No, that's the thing. I didn't have any mods, and I was trying to connect to a vanilla server.
EDIT: And it seems to do it for every server, not just a single one.

[daniel34]

Mods mismatch detected!
base: Mod contents are different even though versions are the same

Your base mod (the base game files) are modified, therefore it doesn't allow you to connect to any server to prevent desyncs.
If you're on Steam then verify the game files, if you use the website version then reinstall the game.