Fix - Prototype 2 Failed To Save Data

The "failed to save data" error in Prototype 2 on PC is typically caused by Windows folder protection, permission issues, or modern hardware conflicts (high CPU core counts). Primary Fixes Allow Through Controlled Folder Access

const saved = await res.json(); // persist locally as cache localStorage.setItem(`proto2:$saved.id`, JSON.stringify(saved)); return saved; catch (error) console.error('SaveProto2 error', error); // optional: enqueue for retry or show user-facing error throw error;

Server-side validation or ORM issues

Navigate to your Steam library.
Right-click Prototype 2 > Manage > Browse local files.
Find Prototype2.exe.
Right-click it > Properties > Compatibility tab.
Check "Run this program as an administrator."
Click Apply > OK.
Important: Launch the game from the .exe or Steam shortcut every time. Do not use a desktop icon that doesn't have admin privileges.

Step 4: The OneDrive Killswitch (Crucial)

Open OneDrive settings (right-click the cloud icon in your system tray). Go to Settings > Backup > Manage Backup. Look for Documents. If it says “Documents are backing up,” click Stop backup. Why? OneDrive sees the game writing a file, tries to upload it, and locks the file mid-write. The game panics and deletes the save. prototype 2 failed to save data fix