Before fixing the error, it helps to understand the culprit. In Rise of the Tomb Raider (and many modern games), developers pack game assets (textures, sound, scripts, and cinematics) into large archive files to improve loading times and organization.
The bigfile.000 is the primary archive file. It is usually several gigabytes in size and contains the core data required for the game to run. If your operating system or anti-virus software cannot read this file, the game throws the "unable to open" error.
Windows 10 and 11’s Controlled Folder Access (part of Ransomware Protection) often blocks games from reading large archives in protected folders like Documents or Program Files. Rise Of The Tomb Raider Unable To Open Bigfile.000
Steps:
BIGFILE.000 is not a corrupt or random file—it is the primary game archive containing most of Rise of the Tomb Raider’s critical assets: textures, sound, levels, and scripts. The game engine needs to read this file to load anything. If the game cannot open it, startup fails immediately. Before fixing the error, it helps to understand the culprit
Modern antivirus software uses "Behavioral Analysis." When Rise of the Tomb Raider tries to read a 10GB+ file (bigfile.000), the AV may flag it as ransomware-like behavior and block access.
For Windows Defender (Windows 10/11):
Try these solutions in order. The first method resolves the issue for 80% of users.