Check your antivirus history to see if it blocked u4.exe or tll.exe . Adding an exception for the game folder often fixes "failed to save" or launch errors.
If you are seeing a "Checksum Error" or "Corrupt Archive" message for this specific part, you can try the following steps to fix it without redownloading the entire set: 🛠️ Common Fixes for Archive Errors UNCHARTEDLegacyThievesCollection.part15.rar
If using Steam, right-click the game > Properties > Installed Files > Verify integrity of game files . Check your antivirus history to see if it blocked u4
Open the first part of the archive in WinRAR , go to the Tools menu, and select Repair archive . WinRAR will attempt to use the "recovery record" (if included) to fix corrupted data. go to the Tools menu