cosmetic mods like UI mods and mods that change the way different portraits work are fine

the easiest way to check is to go to the multiplayer menu, if there are tons of rooms then your mod is fine

I have around 20 mods installed. Wtf why this change

One is enough,including namelists&new species

Originally posted by Watermelon Wolf:

Wtf why this change

This isn't a change. Before 2.0.2, mods could modify the checksum (and so disable achievements, for example). Maybe a mod that you were using before which did not modify the checksum now does modify it in its 2.0.2 version.

So, what if I don't have any mods installed, and steam says my game has no corrupted data either?

Originally posted by Animus:

So, what if I don't have any mods installed, and steam says my game has no corrupted data either?

If you have ever installed a mod, but have uninstalled it, it may not have uninstalled properly and a file may be left behind that is modifying the checksum. If you can locate that file manually and delete it then that might resolve the problem.

If nothing else works you can try this:
- Uninstall the game.
- Delete all the folders that contain(ed) game data.
- Reinstall the game.

Well, deinstallation and re-installation of the game certainly worked.

Ok, I had this problem and try to do the commom folder delete procedure and didn't manage to fix it. The procedure of uninstalling everything and purge all the files, then reinstall de game sure work, but seems to me too extreme.

So I begin to investigate and found a .txt documment in the instalation folder named checksum_manifest.txt. This documents tell the game witch folders to "check" to do the "sum". So, beside the common folder, I deleted the location, map and localisation_synced folder, then made a check folder procedure on steam and re-downloades those folders and, voila! Checksum now is fixed. Try this before uninstalling the game.

Hope this work for you and sorry for the bad english.

Thank you so much Zoe, this really helped a Lot and was just the thing, that made it run for me under Linux, even though there was only a "localisation" and "localisation_synced" folder besides the "common", "map" and "events" folder, which I all deleted - only something below 10 MB or around less than 50 MB at least and after the Integrity Check of the Folders, it worked like a charm. Thanks for pointing out that really easy and effective solution to all of us.

Originally posted by Zoe:

Ok, I had this problem and try to do the commom folder delete procedure and didn't manage to fix it. The procedure of uninstalling everything and purge all the files, then reinstall de game sure work, but seems to me too extreme.

So I begin to investigate and found a .txt documment in the instalation folder named checksum_manifest.txt. This documents tell the game witch folders to "check" to do the "sum". So, beside the common folder, I deleted the location, map and localisation_synced folder, then made a check folder procedure on steam and re-downloades those folders and, voila! Checksum now is fixed. Try this before uninstalling the game.

Hope this work for you and sorry for the bad english.

Thank you dude, this worked!

Hi! I want to bring up something I discovered from this error. I had a Star Wars mod installed ages ago. This mod was not updated and caused the constant checksum modified error in my game, despite reinstalling the game a few times. All I did was remove the mod at the launcher, restart it, and voilá... As brand new. Hope it works for you guys too!

En español: Descubrí que si tienes un mod que por alguna razón no see ha actualizado activo en el launcher, siempre te va a tirar el error del checksum, sin importar si reinstalas mil veces. Hay que desactivar/eliminar el mod en el launcher para que deje de salir ese error. Espero les sirva

It's not it being updated or not that would matter. What matters is if there's an active mod that adds/overwrites game files, that's what the checksum verifies.