Don't Starve is damaged and can't be opened.

First of all, I'm sorry to hear about this.

As a first troubleshooting step, you will need to ensure that your local account on the MacOS device has full administrator privilege to read/write/access your hard drive. You can find more information on administrator privileges for local mac user accounts here: https://support.apple.com/en-ca/guide/mac-help/mtusr001/mac
 
If you have tried the above and the issue persists, you should be able to do a workaround that will allow you to play the game on your Mac OS in the meantime:
 
1) On your Steam Library list, if you click on PLAY for Don't Starve and you will encounter the error message indicating the file is damaged and should be moved to trash, click on the cancel button to close that window.

2) Instead, go back to your Steam Library list, right-click on Don't Starve > Click on "Manage" > and click on "Browse Local Files"; this will open up your installation folder.

3) Right-click on the donotstarve_steam app > select the OPEN button; this will provide another error message indicating the following:
"dontstarve_steam is damaged and can't be opened. You should move it to the trash."

4) On that error message, click on the OPEN button. This will force the Mac OS to launch the game successfully. Once you are able to successfully launch it once this way, you only need to click on the PLAY button on Steam to launch it going forward.

28 minutes ago, DiogoW said:

First of all, I'm sorry to hear about this.

As a first troubleshooting step, you will need to ensure that your local account on the MacOS device has full administrator privilege to read/write/access your hard drive. You can find more information on administrator privileges for local mac user accounts here: https://support.apple.com/en-ca/guide/mac-help/mtusr001/mac
 
If you have tried the above and the issue persists, you should be able to do a workaround that will allow you to play the game on your Mac OS in the meantime:
 
1) On your Steam Library list, if you click on PLAY for Don't Starve and you will encounter the error message indicating the file is damaged and should be moved to trash, click on the cancel button to close that window.

2) Instead, go back to your Steam Library list, right-click on Don't Starve > Click on "Manage" > and click on "Browse Local Files"; this will open up your installation folder.

3) Right-click on the donotstarve_steam app > select the OPEN button; this will provide another error message indicating the following:
"dontstarve_steam is damaged and can't be opened. You should move it to the trash."

4) On that error message, click on the OPEN button. This will force the Mac OS to launch the game successfully. Once you are able to successfully launch it once this way, you only need to click on the PLAY button on Steam to launch it going forward.

THANK YOU SO MUCH!!! This worked no problem and now it launches straight from Steam!!! Such a simple workaround that I hadn't even noticed or been tipped off about!!! Thank you a million times again!!!

Changed Status to Closed

I was having this issue today, perhaps after the introduction of the Midsummer Cawnival, on MacOS Tahoe 26.5.1, and I couldn't "Open anyway" with any of the methods I've seen around so far, including from "Privacy & Security".

The game has worked fine for the past ~5 days (since I first installed DST on a macbook).

The issue seemed to be that the app bundle has been changed:

cd ~/Library/Application\ Support/Steam/steamapps/common/Don\'t\ Starve\ Together
codesign --verify --deep --strict --verbose=2 dontstarve_steam.app

 

The output was that a lot of files were added and the signature fails.

Quote

--prepared:/Users/USER/Library/Application Support/Steam/steamapps/common/Don't Starve Together/dontstarve_steam.app/Contents/MacOS/dontstarve_dedicated_server_nullrenderer
--validated:/Users/USER/Library/Application Support/Steam/steamapps/common/Don't Starve Together/dontstarve_steam.app/Contents/MacOS/dontstarve_dedicated_server_nullrenderer
dontstarve_steam.app: a sealed resource is missing or invalid
file added: /Users/USER/Library/Application Support/Steam/steamapps/common/Don't Starve Together/dontstarve_steam.app/Contents/cached_mod_manifests/workshop-2431691504.manifest.version
file added: /Users/USER/Library/Application Support/Steam/steamapps/common/Don't Starve Together/dontstarve_steam.app/Contents/cached_mod_manifests/workshop-2431691504.manifest
...
many more files added

 

The game wrote mod caches and MOTD images into its own bundle, which Tahoe now enforces against. The signature seal broke (for the first time). A denial got cached by the apple gatekeeper, and every subsequent launch demanded an un-approvable BundleIntegrity prompt (even after the bundle was clean again). The Gatekeeper rejection breadcrumbs cache-key is the bookmark/inode, which a fresh copy doesn't inherit.

So I first removed the newly added files:

cd ~/Library/Application\ Support/Steam/steamapps/common/Don\'t\ Starve\ Together/dontstarve_steam.app/Contents

# Remove everything that was "added" after signing
rm -rf cached_mods/* cached_mod_manifests/* mods/workshop-* data/images/motd_box*.tex

# Clear attributes and confirm the seal is intact
sudo xattr -cr ~/Library/Application\ Support/Steam/steamapps/common/Don\'t\ Starve\ Together/dontstarve_steam.app
codesign --verify --strict ~/Library/Application\ Support/Steam/steamapps/common/Don\'t\ Starve\ Together/dontstarve_steam.app && echo "SEAL OK"

 

And then created a fresh copy of the game in order to work around the cached rejection:

cd ~/Library/Application\ Support/Steam/steamapps/common/Don\'t\ Starve\ Together/dontstarve_steam.app

# Replace the canonical bundle with a fresh-identity copy (no rejection history)
rm -rf dontstarve_steam.app.new
cp -R dontstarve_steam.app dontstarve_steam.app.new
sudo xattr -cr dontstarve_steam.app.new

# Swap: move old aside, put fresh copy in canonical place
mv dontstarve_steam.app dontstarve_steam.app.old
mv dontstarve_steam.app.new dontstarve_steam.app

# Confirm seal
codesign --verify --strict dontstarve_steam.app && echo "SEAL OK"

 

After I tested that the game works, I cleaned up the backup of the game:

rm -rf ~/Library/Application\ Support/Steam/steamapps/common/Don\'t\ Starve\ Together/dontstarve_steam.app.old

 

Edited June 26 by dihorul_pestrit
Added information about the MacOS version used.